Volume s1-21, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



The 226 positive and 172 negative smears accruing during the daily (in some instances every second day) examination of the peripheral blood of fifty canaries mosquito-infected with (Hartman) have been studied with the object of arranging them according to the time required to count a given number of asexual organisms. It was observed that the rate of progression and diminution in these infections occurred in such manner that a system of plus counting could be devised as follows.

  1. Negative—No organisms in 3 minutes
  2. 1+—Less than twenty organisms in 3 minutes
  3. 2+—Twenty organisms in 2 to 3 minutes
  4. 3+—Twenty organisms in 1 to 2 minutes
  5. 4+—Twenty organisms in 30 to 60 seconds
  6. 5+—Twenty organisms in 30 seconds or less
I believe this to be a simple, quick and reliable method of determining the degree of infection upon a comparative basis for all ordinary practical purposes.


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