1921
Volume s1-19, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645
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Abstract

Summary

Experiments with six forms of the complex and with are discussed. Larvae were kept for three days at 27°C. in solutions of sodium chloride, potassium chloride, magnesium sulphate, and calcium sulphate, and the percentage of larvae surviving was recorded. By this means large numbers of experiments could be made, and the method may have a wide application in the study of larval survival and food requirements. It was found that the seven forms studied showed distinct differences in their toleration for the salt solutions used, differences which may be summarized thus:

. This species seems to have less need for calcium than any of the other species studied: a characteristic which enables some larvae to survive in relatively high concentrations of magnesium sulphate without the addition of a calcium salt. differs markedly in this regard from all other forms studied. In the presence of calcium is relatively tolerant of sodium chloride and it is somewhat more tolerant of potassium chloride than any of the other forms. Comparison experiments with material from North Germany, England, Portugal, Hungary, and Italy did not show any differences that seemed significant.

. The tolerance of this species for sodium chloride seems identical with that of . It differs sharply from , however, in its calcium requirements, and probably because of this it shows a greater mortality than in solutions of magnesium sulphate and potassium chloride when calcium is not added. It is interesting that in experiments with minimum amounts of calcium sulphate showed the same survival as and .

, and . The experiments reported here do not show any very striking differences between these three forms. The material available was inadequate for our purposes so that no experiments could be made with anything except sodium chloride and sea water, and the results of those experiments are contradictory. seems to be consistently more tolerant of sodium chloride than , but the difference is not striking, and no differences are apparent in the experiments with other salts.

. This species differs markedly from all of the others in its greater tolerance of sodium chloride. The experiments with other salts were inadequate to form the basis of any conclusions.

. The prime characteristic of this species is its inability to survive in media in which there is not a readily available supply of calcium. In the presence of calcium its tolerance for sodium chloride is similar to that of .

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/content/journals/10.4269/ajtmh.1939.s1-19.357
1939-07-01
2017-09-25
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