The American Journal of Tropical Medicine and Hygiene - Volume s1-29, Issue 5, 1949

• 1.  Only three previous attempts have been reported in which the guinea-pig has been exposed to infection with Endamoeba histolytica. Two of these (Baetjer and Sellards, 1914 and Chatton, 1917) were partially successful in producing tissue invasion and one (Werner, 1908) was unsuccessful.
• 2.  The study herein reported consisted of a planned experiment to inoculate stock guinea-pigs under strictly aseptic technic with a strain of Endamoeba histolytica of human origin. Cultured trophozoites in numbers varying from 200,000 to 7,000,000 were introduced into the terminal ileum and the animals were sacrificed in groups of five at daily intervals from one to seven days following inoculation. Six uninoculated animals served as controls.
• 3.  On sacrifice the terminal ileum and entire large intestine were removed intact, as was the liver. The several levels were grossly inspected for suspicious amebic lesions, then these levels, designated A (terminal ileum), I (cecum), II (ascending colon), III (transverse colon), IV (descending colon) and V (rectum), were separated from one another, pH determinations made on representative animals at levels I, III and V, the fecal contents carefully studied for evidences of E. histolytica and for the natural parasites of the guinea-pig's intestine, and segments of the intestinal wall at each level fixed in Bouin's fluid, sectioned and studied microscopically.
• 4.  The natural parasites of the guinea-pig which were identified from cecal and colonic feces were: Balantidium caviae, Chilomastix intestinalis, Trichomonas caviae, Spiromonas angusta, a Bodo-like flagellate, Eimeria caviae and once the oxyuroid nematode Paraspidodera uncinata. Except for B. caviae and Eimeria caviae, none of these organisms are tissue invaders. In no instance was there evidence that any of these organisms had assisted in the production of the amebic lesion. It was found that examination of passed fecal pellets was an unreliable method of diagnosing these infections.
• 5.  Endamoeba histolytica was recovered from the intestinal feces in 8 of the 15 animals sacrificed on days 1–3 after inoculation, whereas typical amebic lesions were found in all 15. During days 4–7 the amebae were found in 19 of the 20 sacrificed animals and typical amebic lesions in 19, although the exceptions in each category were not coincidental. With two exceptions the lesions were confined to the cecal area; E. histolytica trophozoites were most frequently and abundantly recovered from this level but they were relatively common in the feces at levels A and II, occasionally at levels III and IV, and once at level V. The six control animals had the same natural fauna and flora found in the experimental series; in none of them were there any lesions of the intestinal wall in levels A and I–V.
• 6.  The amebic lesions consisted of two types, (1) shallow excavations with a relatively wide diameter, and (2) deeply penetrating ones with a small orifice. Histologically some lesions consisted essentially of lytic necrosis without evidence of bacterial invasion and without host-cell reaction, and others with inflammatory reaction in which neutrophilic leukocytes and fibrocytes were predominant.
• 7.  Amebic infection produced an appreciable increase in the pH at level I, slight increase at level III and no change at level V.
• 8.  Spontaneous amebic lesions of the liver were found to be uncommon compared with lesions of undetermined origin observed in the guinea-pig's liver.
• 9.  Amebiasis in the guinea-pig causes loss in weight, anorexia, reduced activity and deterioration in the appearance of the fur.
• 10.  This study has conclusively demonstrated the high susceptibility of the guinea-pig to infection with a pathogenic strain of Endamoeba histolytica under the conditions of the experiment. It suggests the need to determine the rôle of the bacteria associated with the amebae in the inoculum, the relation of the nutritional status to susceptibility, the relative infectivity of cysts inoculated by mouth or intragastrically vs. trophozoites introduced into the terminal ileum, and possible differences in infectivity of other strains of E. histolytica.

Cysts of the NRS strain of E. histolytica were exposed to various concentrations of ozone in aqueous solution for varying time intervals and under varying conditions oftemperature, organic nitrogen, and pH. The criterion of survival of cysts so exposed was their ability to establish growth in culture compared with that of untreated controls.

In 8 preliminary experiments with varying 5-minute ozone residuals, the treated cysts were planted in numbers of 3,000 to 4,000 cysts per tube. Completely negative results were obtained with 5-minute residuals of 1.8 P.P.M̄. and above. With lower residuals some positive cultures were obtained. However, the method of planting cysts did not permit estimation of the amount of cyst survival in these instances.

In further experiments with 5-minute ozone residuals, both control and treated cysts were planted in series of decreasing numbers. Results with the control cysts indicated that the presence of an average of 10 cysts per tube almost invariably would result in a positive culture. In addition, growth expectancies were obtained when averages of 8 and 4 untreated control cysts were present per culture tube. These data were used as a basis for estimating cyst destruction when treated cysts were planted in numbers varying arithmetically from 2,000 to 125 cysts per culture tube. The results of 15 experiments indicated a cyst destruction of 98 to more than 99 per cent with 5-minute ozone residuals of 0.3 P.P.M̄. and above, resulting from ozone applications of 0.7 P.P.M̄. and above.

In experiments designed to evaluate the importance of contact time, cyst samples were deozonized ½, 1, 3, 5, and 10 minutes after application of ozone ranging from 0.3 to 0.8 P.P.M̄. For the evaluation of the results of these experiments, another method of planting cysts in decreasing numbers was employed, in which the numbers varied logarithmically. The results of 18 experiments indicated that the prolongation of the exposure period beyond 1 minute did not effect a measurable, consistent increase in cyst destruction. It was estimated that 96 to more than 99 per cent of the cysts were destroyed after 1 minute in all experiments, the greater variation in percentage destruction occurring between experiments rather than between the exposure periods of a single experiment.

The following variations in experimental conditions were evaluated with regard to their possible influence on the cysticidal action of ozone; Temperature, 10° to 27°C.; pH in the 6.5 to 8.0 range; distilled water compared to tap water; and organic nitrogen in the range of 0.14 to 1.25 P.P.M̄. Such variations provided neither consistent nor marked differences in the results obtained, probably because of the high degree of cyst destruction under all conditions employed.

In general, it is concluded that ozone in aqueous solution is highly cysticidal for E. histolytica and that the cysticidal action does not appear to be influenced to any great extent by pH, temperature, or organic nitrogen. It is concluded, further, that the evaluation of cysticidal agents by cultural means should employ a method of planting treated cysts in decreasing numbers whereby cyst destruction can be estimated in instances in which it is not complete.

• 1.  Bismuthoxy p-N-glycolylarsanilate (Win 1011; “WIA”) is amoebacidal in vitro at a dilution of 1:30,000 to 1:35,000 when tested against Endamoeba histolytica in Hansen's egg infusion medium.
• 2.  7-Iodo-4-(1-methyl-4-diethylaminobutylamino)quinoline diphosphate (Win 246; SN-7620-5) is amoebacidal in vitro at a dilution range of 1:3,000 to 1:7,500; it is slightly more active than chloroquine diphosphate (Win 244; SN-7618-5). Both compounds are more active than chiniofon or diiodo-oxyquinoline under similar conditions.
• 3.  Examination of the cecum showed that all hamsters (C. auratus) of our colony weighing more than 75 grams were naturally infected with Endamoeba criceti, and it was demonstrated that a five day course of oral medication with carbarsone, chiniofon or diiodo-oxyquinoline resulted in elimination of this infestation. It was concluded that the natural infection of the hamster with E. criceti is suitable for testing the amoebacidal activity of compounds which might be expected to reach the large intestine in sufficient concentration to be effective in the treatment of intestinal amoebiasis.
• 4.  Win 246, the iodine analog of chloroquine, is effective in freeing hamsters of their intestinal amoebae when administered at toxic levels; chloroquine is ineffective in hamsters at dose levels which are lethal in five days.
• 5.  Win 1011 is highly effective in clearing hamsters of E. criceti. The activity of this drug on a weight basis is greater than that of chiniofon or diiodo-oxyquin-oline and is slightly less than the activity of carbarsone. Win 1011 did not produce any evidence of toxicity when administered to hamsters for five days at ten times the dose level required to clear all test animals; carbarsone caused deaths when the dose level was three times greater than that required to clear all test animals.
• 6.  Win 1011 appeared to be completely nontoxic when given orally to humans in therapeutic doses of 0.5 gm three times daily for ten days. In view of the low toxicity and preliminary reports of therapeutic efficacy in the treatment of intestinal amoebiasis it is recommended that Win 1011 be given a more extensive clinical trial and careful evaluation.

• 1.  The observations recorded indicate that percussion provides a practicable means of detecting non-palpable enlargement of the spleen.
• 2.  A simple technique of examination, and percussion criteria of enlargement are recommended.
• 3.  Controversial points are considered.
• 4.  The limitations and value of splenic percussion are briefly discussed.

• 1.  A malaria survey of the southern territory of the peninsula of Lower California reveals endemic malaria (P. vivax) in the towns of Mulegé, Santiago, San José del Cabo and Todos Santos. In 805 children examined, the spleen rate was 19.3 and the parasite rate 7.8.
• 2.  Anopheles pseudopunctipennis var. typicus is the sole anopheline and the vector of malaria in the region.
• 3.  Control of malaria by DDT residual spraying of dwellings is recommended.
• 4.  Eradication of anophelines would be a possibility in the regions visited.

In 1938 Coggeshall and in 1944 Maier and Coggeshall (1, 2) showed that Plasmodium knowlesi in rhesus monkeys could be eliminated by various sulfonamide drugs and that the residual immunity as tested by reinoculation with the homologous parasite was of a mild degree and of relatively short duration. Unfortunately there were no antimalarial compounds which could be relied upon to exert similar action in human malaria until Alving and others (3, 4) demonstrated that pentaquine would eradicate acute and chronic vivax infections. Since these patients were treated and observed in nonendemic area, there was no problem of differentiating relapses from initial infections. Furthermore, all treated subjects were healthy male prisoners who had volunteered to be inoculated by the bites of infected mosquitoes and were still available for observation. Such a combination of circumstances provided an unparalleled opportunity for investigating the status of immunity in human malaria.

Visceral leishmaniasis (Kala-Azar) has been reported with increasing frequency in the United States during the past two years. Search of the literature reveals the appearance of some thirty odd exogenous cases from various sources (1, 2, 3, 4, 5). Doubtless still other cases have been diagnosed and are as yet unpublished. Previous papers have adequately discussed the etiology, epidemiology, pathology, clinical and laboratory findings, and treatment of this disease (1, 2, 6, 7, 8). This report presents a case exhibiting the longest recorded interval between presumptive cure and relapse, two years having passed since “cure” was established and the first appearance of symptoms suggesting recurrence of activity.

REPORT OF CASE R. G., a 32 year old white male, was admitted to the Veterans Administration Hospital, Washington, D. C., on November 2, 1947, complaining of intermittent fever of about four months duration with recent onset of general malaise and chills accompanying the fever.

Since Davis and Cox (1) first isolated the causative agent of Q fever from Dermacentor andersoni, several species of ticks have been incriminated in the epidemiology of this disease in various parts of the world. Investigations implicating the following species were reviewed by Kohls in 1948 (2): in Australia, Haemaphysalis humerosa and H. bispinosa, Ixodes holocyclus, Rhipicephalus sanguineus and Boophilus microplus; and in the United States, Dermacentor occidentalis, Amblyomma americanum, Haemaphysalis leporis-palustris, Ixodes dentatus, Ornithodoros moubata and O. hermsi.

Recently Q fever has been demonstrated to occur sporadically in Panama (3, 4). However, there are no data available concerning the possible vectors in this area. We decided, therefore, to attempt experimental transmission by Amblyomma cajennense, a tick ideally suited for this purpose in Panama, due to its abundance and wide host range (5). The JD strain of Rickettsia burneti, isolated locally (6), was employed as the infective agent and the guinea-pig as the experimental animal.

When Doctor J. B. Christopherson introduced in the Sudan, the treatment of schistosomiasis with intravenous doses of tartar emetic, he stressed the importance of watching the gradual degeneration of the escaping ova as an estimate of successful cure, and, under the Streatfeild Research Schlarship from 1919 to 1922, I noted the same signs in ova of Schistosoma mansoni, S. bovis and S. spindale.

Sir Leonard Rogers has emphasized the value of the eosinophil count as a means of determining successful treatment, the percentage rising as soon as antimony injections are administered and settling down to normal a few weeks after all the adult worms have been destroyed, but the complement-fixation test has not proved so reliable, and for many the blood count and examination of escaping ova suffice as laboratory tests.

A mere absence of escaping ova may be due to various causes, and is common from some general disturbance of health, so that no reliance can be placed on it in judging that all the adult worms are dead.

A case of Schistosoma mansoni infestation is reported in a 32 year old Puerto Rican woman, who had been out of the endemic area and a resident of New York City for 26 years. Evidence was adduced that this patient had living adult flukes in her body alive at least 26 years an extension of the known life span of this parasite.

Review of the literature reveals that S. hematobium has been known to have an equal longevity and that the same has been reported with S. japonicum but not as well as can be determined, ever before with S. mansoni.

The association of polypoid schistosome granuloma with possible malignant transformation is again noted.

In view of the experimental evidence presented in these pages the following points are made:

• 1.  A total of 204, or 41.8 per cent, of the 487 tests run on samples of Army uniform cloth were positive for the passage of small numbers of cercariae of S. japonicum through the cloth.
• 2.  The actual number of viable cercariae of S. japonicum that succeeded in effecting a penetration of the samples of Army uniform cloth tested in the in vitro experiments was low. Only 652, or 2.63 per cent, of the 24,350 cercariae used in these experiments penetrated the cloth compared with 62.5 per cent of the controls.
• 3.  The results of the in vitro experiments show that the different types of cloth permitted the passage of cercariae in increasing numbers in the following order: Water resistant sateen—new; water resistant sateen—washed four times; herringbone twill—old fatigue cloth; cotton khaki twill—old trousers; cotton khaki twill—new trousers; herringbone twill—new fatigue cloth; woolen O.D. trousers—new; cotton khaki twill—new shirt; woolen O.D. trousers—old; woolen O.D. shirt—new; cotton khaki twill—old shirt; woolen O.D. shirts—old.
• 4.  Evidence is presented to show that when pressure is applied to pieces of test cloth greater numbers of the tests become positive and greater numbers of cercariae are successful in penetrating the cloth.
• 5.  The recovery of adults of S. japonicum from mice exposed to cercariae that had successfully penetrated samples of test cloth suggests that these parasites are still capable of infecting man.
• 6.  Adult schistosomes were recovered from mice that had been exposed to cercariae-infested water protected only by bags of test cloth. The number of adults recovered was essentially the same as those recovered after exposure to cercariae that had penetrated the cloth in the in vitro experiments.
• 7.  It is evident from the foregoing experiments that all types of Army uniform cloth afford some degree of protection to the wearer. Herringbone twill (fatigue cloth) and khaki cotton twill would appear to give slightly better protection than new woolen O.D. material. However, any uniform trouser material would protect the legs provided it was tucked into the top of combat boots and enough slack was present to form a cuff over the boot top.

• 1.  From the experimental work with A. p. punctulatus it appears that this species of mosquito is a vector of filariasis in this area.
• 2.  The first generation of mosquitoes reared in the laboratory is probably much more hardy than later generations and is less liable to show a high rate of mortality.
• 3.  It is quite practical to make photomicrographs without all of the attachments generally considered necessary for this type of work. Such equipment is expensive and unavailable in most areas and may be improvised.
• 4.  It is believed that this is the first time that the complete larval development of W. bancrofti in a mosquito host has been photographed at a magnification which demonstrated structural detail and that this system of “micro-mapping” might be used more often under similar circumstances.

• 1.  Ten species of mosquitoes representing five genera: Anopheles, Aëdes, Culex, Armigeres, and Tripteroides were discovered on the Treasury Islands.
• 2.  Of the mosquito-borne diseases known to be endemic in the South Pacific, malaria was of primary importance on Stirling and particularly Mono Island in the Treasury group.
• 3.  Dengue has never been reported, and a 0.7 per cent infectivity rate for Wuchereria bancrofti was reported in the native inhabitants of Falamai village on the south coast of Mono Island.
• 4.  A key to the fourth instar larvae is given and a brief discussion relative to the taxonomy and biology of the reported species is presented.

The list of diseases associated with mites and especially with the liponyssid mites has been reviewed.

A method for rearing and maintaining mites that permits the continuous observation of individual mites during their entire life has been described.

The observations on the effect of temperature and relative humidity appear to establish within rather narrow limits the conditions of the micro-environment under which the mite can multiply either in the laboratory or in nature. Since the eggs are always laid away from the host, the natural environmental temperature determines their hatching. Egg laying, and therefore reproduction, does not occur at 6° to 8°C., although the adult may live for more than a month at these temperatures. Eggs are laid and protonymphs develop at 12° to 14°C. Protonymphs in nature feed on the body of the rat deep within the fur and protected from a cold environment. It appears likely that 12° to 14°C. represents the lowest temperature at which L. bacoti can reproduce, and then only with a great lengthening of the cycle and an increase in mortality.

At low and intermediate temperatures, these mites can tolerate a wide range of relative humidity. At 24° to 26°C., they withstood a relative humidity of 18 to 20 per cent. However, with increasing temperatures, increasing humidity is necessary to permit survival. Slightly over 60 per cent relative humidity is necessary to permit a complete cycle at 34° to 36°C., while even at 100 per cent relative humidity all mites died at 36° to 38°C.

At least for the temperatures and relative humidities studied, the conditions of the open laboratory (24° to 26°C. and 47 per cent relative humidity) gave the best over-all opportunity for development and permitted rearing to the adult stage of 62.5 per cent of some 627 eggs studied under those conditions. There was, however, some evidence that humidities higher than 47 per cent are more favorable to survival of the egg. In the open laboratory, the average life of the adult female was 61.9 days and the average number of eggs per female 98.8; a little over ¾ of the mites reached the adult stage between the 11th and the 16th day. These figures suggest a considerable reproductive ability in L. bacoti and, since they undoubtedly reflect some mortality due to handling, it may be that the mites reproduce even more efficiently in nature under favorable conditions.

Observations in January and February 1948 at Savannah showed the lowest temperature of even the accessible portion of both protected and unprotected Rattus norvegicus burrows was 7.2°C. while the highest temperature was 20.5°C. The relative humidity of these burrows was usually over 90 per cent but never as high as 100 per cent. Temperature changes in the burrows always lagged behind and were less marked than those of the environment. The average burrow temperature in winter was warmer than the environmental temperature. These observations suggest that, even in the coldest months of winter, many days occur in the Savannah climate which could permit some reproduction of L. bacoti.

The laboratory studies suggest some of the factors which may be expected to favor the appearance of excessive numbers of L. bacoti or to greatly reduce these ectoparasites in nature.

No significant difference occurred in the total egg production and in the length of the adult period of fertilized and unfertilized females. Unfertilized eggs developed parthenogenetically into male offspring which as adults, were capable of fertilizing female adults.

• 1.  An evaluation in terms of Phlebotomus control has been made of the extensive DDT-malaria campaign which has been in progress in Greece since 1946. Observations were made in Attica and Crete throughout the sandfly season of 1948.
• 2.  In unsprayed places the sandfly population was normal in abundance and distribution of species when compared with the reports of previous investigators. Nearly 3000 sandflies were caught and identified.
• 3.  Sprayed buildings were uniformly negative for Phlebotomus of any species. Night observations out-of-doors showed sandflies to be at a very low level within sprayed areas. The testimony of the people was solidly to the effect that sandflies had been annoyingly abundant but ceased to bother them indoors after the first treatment, and that there has been little or no annoyance outdoors at night.
• 4.  The reduced sandfly abundance in the cities of Athens and Canea, Crete, which have not been sprayed in toto, may be due in part to the peripheral effect of the many treated buildings scattered through the urban areas, and in part to the use of household sprays—factors which have not been measured.
• 5.  A modification of the oiled paper trap is described.
• 6.  The present status of leishmaniasis in Canea is compared with that of previous years.

• a.  A very marked decline of kala azar had occurred prior to the use of DDT, and was associated with the destruction of infected dogs and the general reduction of the dog population. With the return of dogs to normal, it is difficult to assess the effect of the present low sandfly level because of lack of information about factors such as other reservoirs and normal kala azar cycles.
• b.  A sharp drop in oriental sore with the development of relatively few cases in the last two years, coincided with the introduction of DDT in 1946.
• c.  Definite conclusions on leishmaniasis control must await long-term observations in endemic foci.
• 7.  A recently initiated project for the control of oriental sore in the Abruzzi, Italy, was visited. Observations on the dominant sandfly and supposed vector, P. perfiliewi, were made in treated and untreated areas. There was witnessed the actual destruction of great numbers of sandflies on encountering residual DDT, resulting apparently in the progressive reduction of the local sandfly population.
• 8.  In Sardinia, where every man-made structure has been treated with DDT, houses were negative eight or nine months later, and sandfly incidence was at an extremely low level.
• 9.  On the basis of the present and previously published work, the following general conclusions seem warranted:

• a.  Treatment of interiors with residual DDT gives immediate and virtually complete protection from sandflies indoors.
• b.  House spraying alone, in compact communities, with an annual, preferably pre-season, treatment, eventually reduces the Phlebotomus population within the sprayed areas to near the vanishing point.

It seems reasonable to draw the following conclusions from the Cuba experiment and its background;

• 1.  Female calls of wild-caught anophelines obtained from a cattle trap such as A. albimanus can be recorded, and a re-recorded test record obtained of sufficiently good quality to be effective for sound-baiting a trap to catch males of the same species.
• 2.  The calls which seem of lowest pitch as judged by the human ear are seemingly the most effective for calling the males.
• 3.  The female calls used are not sine-wave in shape but are quite complex, and are not audible ordinarily to the unaided human ear.
• 4.  A test record of female sounds as described in (1) will cause males of the same species to fly in the direction of the loudspeaker. An electric screen (high-voltage-charged) can be placed forward of the loudspeaker for the purpose of killing the mosquitoes that fly toward it. The characteristics of the power supply chosen for the screen can be of such nature as to cause practically no damage or distortion in the killing process that may interfere with the accurate identification of the species and sex of the mosquitoes killed.
• 5.  The mosquitoes so electrocuted are predominantly males (90 per cent) of the species for which the female call is recorded and played.
• 6.  The playing of such a record will also attract frogs, chameleons, bats, dragon flies and other forms of life that prey upon the mosquitoes for food. Certain will be attracted and killed (tree frogs, chameleons); others (bats, dragon flies) will dart around but will not be killed as they do not touch the electric screen.
• 7.  Neither the light flashes produced by the electric discharges, nor the ozone produced seem to have any affect in attracting or repelling the subject mosquitoes.
• 8.  The peak flight time of Anopheles albimanus occurred substantially at the same time during each evening of the test (7:15 PM local Cuban time).
• 9.  The numbers of mosquitoes trapped during a peak period of ten minutes exceeded the number of mosquitoes taken from a cattle trap in a week or more.
• 10.  The numbers of mosquitoes trapped each night varied over a fairly wide range from night to night.
• 11.  The playing of such records seemingly will not induce flight activity in male mosquitoes at times when they are not normally active, but will, during periods of normal activity, alter their flight course so that such insects can be killed in a trap.
• 12.  The sound level used in reproducing the records for a sound-baited trap may be quite high compared with the sound level that the mosquito normally utilizes in nature, but it may not be indiscriminately high as there appears to be an upper threshold beyond which a repellant action may take place. Under very quiet natural conditions, the sound level at this upper threshold is such that the sounds can be heard by an unaided human ear some one-fourth of a mile away. It may prove impracticable to use sounds above this threshold for repellant purposes as their unpleasant nature is objectionable.
• 13.  Peak flight time occurred about 20 minutes after official sunset time. At this time the light level measured on a Weston Master II Exposure Meter was about 0.2 candle per sq. ft.
• 14.  Automatic electrical counting of the electric screen discharges is practicable and whenever possible should be used in the collection of counting data in future field experiments. The electrical count should be compared with the count of mosquitoes found on the sheet in the trap.
• 15.  Sound recording techniques may make possible a valuable quantitative sound-activity index for measuring the sound activity of a particular species of mosquito. Such indices may be derived statistically from the curves automatically traced by an instrument such as an Esterline-Angus continuous-writing DC milliameter energized from a suitable electronic rectifier and filter integrating sound level with time. The electronic rectifier and filter mentioned is energized from the output of the sound recording equipment (capable of recording single insects) that is set to operate continuously over 24 hours or other specified intervals. This method can measure quantitatively regardless of species and sex.
• 16.  Playback of the sound recordings of female mosquitoes to males of the same species under natural conditions (such as in a swamp) can provide a valuable quantitative activity index based on flight. This flight activity index may be compared with the sound activity index of item 15 for statistical correlation. Playback of the sound recordings of one sex to another may be made in the laboratory to measure the sound response to obtain a sound response index, another potentially useful activity index.
• 17.  Electrical insect-killing methods seem selective, and an arrangement that is effective for one kind of insect, say a fly, may not be satisfactory for another kind of insect, say, a mosquito or a beetle. Important factors are:

• a.  Peak voltage
• b.  Energy released per discharge
• c.  Nature of the current with regard to frequency and waveform

• 1.  Line frequency alternating current (60 cycles per second or other)
• 2.  The discharge from a capacitor previously charged to a high voltage (The discharge rate may be quite important).
• 3.  The discharge of an ultra high frequency generator (functioning at say, 50 megacycles per second).
• 4.  Other (e.g. a “spike” generator—such as is used in radar).
  
  For mosquitoes where a minimum of distortion is desired due to electrocution, the simplest arrangement using line frequency alternating current is satisfactory although it may be definitely lethal for accidental contact of human beings or farm animals or the like.
• 18.  It is possible that the heavily haired male antennae act as a receptor mechanism for sound emitted by the female.
• 19.  The sounds are substantially species specific, Aedes will not respond to Anopheles or vice versa.

• 1.  All mosquito sounds are composed of a well-defined fundamental in the center of the audio range together with overtones, even in the case of sounds that sound like clicks. In some spectrograms as many as 15 distinctive frequency bands are recognizable.
• 2.  All mosquito sounds have vibrato effects. Some species show tones with a single warble rate; others show double warble modulation. A common rate for the low frequency warble is from 2 to 15 cycles per second; the higher rate, when present, is often 5 times the lower. The magnitude of the lower rate may be some 5 to 10 per cent; the higher rate is about one-fifth to one-tenth the lower.
• 3.  Male sounds are usually more broken than the female. In most cases the apparent pitch of the male is higher than the female of the same species despite but a small difference in their fundamentals. Mosquito sounds show a change of pitch with time; some increasing as much as 25 per cent in as little as 0.05 sec.
• 4.  The intensity is modulated in all sounds. In some cases modulation is a complete interruption of an entire band or bands; in other cases, harmonics are varied only, leaving the remainder unaffected.

The spectrograms shown above are presented for the purpose of indicating some of the possible applications of modern electronic methods and apparatus in the study of the sounds of disease-carrying mosquitoes. They were made available to us through the courtesy of Dr. Oliver E. Buckley, President of the Bell Telephone Laboratories Inc. to whom we owe a debt of thanks not only for providing them, but also for his most welcome encouragement in our application of modern electronic apparatus to our study. It is the authors' considered opinion that the intensive application of such apparatus will make possible the precise, rapid, and simple observation of natural phenomena related to the sounds of disease-carrying mosquitoes and should lead to the more effective control of such mosquitoes and of the diseases that they transmit.

I have just received the Proceedings of the 4th International Congresses of Tropical Medicine and Malaria, in which there appears my paper on “The relationship of the Haemoflagellates.”

On p. 1113 of this paper 2 lines have been interchanged with the result that this part of the text is incomprehensible.

It is now too late for any alterations but the error could be rectified by drawing attention to it in the American Journal of Tropical Medicine.

I should therefore be very grateful if you could see your way to inserting in your journal a note as follows:—

Petr Wygodzinsky. Elenco Sistematico de los Reduviiformes Americanos. Spanish-English. Pp. 102, wrap. Monograffa No. 1, Instituto de Medicina Regional, Universidad Nacional de Tucuman, Secretaria de Educacion de la Nacion, Tucuman, Republica Argentina, 1947.

Report by the Dean, London School of Hygiene and Tropical Medicine (University of London) Incorporating the Ross Institute. Report of the Work of the School for the Year 1947–1948. Fifty Years of Tropical Medicine, 1899–1949. pp. 138, illus., wrap. Keppel St., Gower St., London, W. C. 1, England.

Missão de Combate às Tripanossomíases. Relatorio Anual de 1947. Colonia de Moçambique. Imprensa Nacional de Moçambique. Lourenço Marquez. 1948.

George R. Moon. How to Become a Doctor. Pp. 131, illus. cloth. Philadelphia, The Blakiston Co., 1949. $2.00.

N. Gohar. Mycoses and Practical Mycology. With a Foreword by Sir Philip Manson-Bahr. pp. xi plus 234; figs. 134; 4 colored plates. Cloth. Baltimore, Williams and Wilkins Co., 1948. $6.00.

Brian Maegraith. Pathological Processes in Malaria and Blackwater Fever.

This scholarly and thought provoking review will be welcomed by all those technically concerned with mosquitoes, while others with broader or differing interests may enjoy reading its interesting pages, summarizing what is known of the behaviour of mosquitoes. The natural history of adult mosquitoes is discussed in five chapters, treating of environment, survival and dispersal, sexual behaviour, food habits, terminating with egg development and oviposition. A chapter devoted to eggs is followed by a sequence of four chapters treating of larval environment, physiology and behaviour, biological environment and classification of habitats, which is succeeded by a chapter on pupae. Their relation to other organisms preceeds other chapters presenting their roles as vectors of viruses and plasmodia. The concluding chapter discuss the species problem, classification, distribution, techniques, and the strategy of research. An appendix gives a classified synopsis of mosquito species, as well as a useful bibliography.

Although certain to be widely useful to those concerned with practical problems involving mosquitoes, the work, notwithstanding is primarily directed to students of general biology, in the hope that they will come to appreciate the potentialities of mosquitoes as experimental animals, conveniently available for the study of fundamental biological problems.

The volume is an attempt to define, from an extensive review of the literature, the basic physiological and pathological processes which determine the reaction of the body to invasion by the malaria parasite and the appearance of blackwater fever, with especial attention to the blood, liver, kidney, brain, spleen, bone marrow, adrenals and heart. The author concludes, from the fragmentary data available, that certain processes, including generalized anoxemia, vascular endothelial damage, together with local and general circulatory changes, the combined effect of which results in the production of tissue anoxia, are common to the development of lesions in all of the organs.

Documenta Neerlandica et Indonesia de Morbis Tropicis (Quarterly Journal of Tropical Medicine and Hygiene). Ch. W. F. Winckel, Editor, Inst. Trop. Hygiene, 57 Mauritskade, Amsterdam O, Netherlands. Vol. 1, No. 1, March, 1949. Subscription per annum Hfl. 12, or $4.50, or 22/6, sent to Riverenlaan 268, Amsterdam Z, The Netherlands.

Revista Brasilera de Malariologia. Publicada trimestralmente. Redactor-Secretario, Dra. Wanda C. Garcia, Serviço Nacional de Malaria, Rua Melo e Souza, 142, Rio de Janiero, D. F., Brasil. Vol. 1, No. 1, Janiero, 1949. Gratis.

Zeitschrift für Tropenmedizin und Parasitologie. Herausgegeben von Dr. E. G. Nauck, Prof. Dr. E. Reichenow, Prof. Dr. H. Vogel, Bernard Nocht Institut für Schiffs- und Tropenkrankheiten, Hamburg 4, Germany. Four issues per annum, subscription per volume D. M. 58. Georg Thieme, Verlag, Diemershallenstrasse 47, Stuttgart-O, Germany.

The Chinese Review of Tropical Medicine. Editor-in-Chief, S. L. Hung. Vol. 1, No. 1, January 1948. Published by Institute of Tropical Medicine of the National University of Taiwan, Taipeh, Taiwan, China.