182 1922 
blood. Furthermore, better growth was obtained in 0.5 per cent 
agar with 5 per cent blood than in 2 per cent agar with 5 per cent 
blood, showing that the amounts of blood being equal, the result- 
ing harder consistence of the latter due to a greater proportion 
of agar contained in it has given rise to lessened suitability of 
the medium for growth of the parasites. 
The Philippine Journal of Science 
TABLE 4.—Leptomonas ctenocephali grown in 2 per cent agar plus different 
percentages of defibrinated rabbit's blood. Cultures inoculated Decem- 
ber 1, 1920. 
Date of examination. 
5 per cent blood. 
10 per cent blood. 
25 per cent blood. 
Very few living organisms 
Very few living or- 
Very few living or- 
December 2, 1920. 
ganisms. ganisms. 
SOMO growths. es jokes san en ck Some growth--____-. Fairly abundant___.| December 3, 1920. 
Do -- Fairly abundant__..| Numerous-_-_-----_-- December 6, 1920. 
PIOMOPOUS (oo bua cS uous cour dans Numerous--__------. Very numerous- --_. December 11, 1920. 
Good growth. -_... do ..| Very numerous, | December 17, 1920. 
many rosettes. 
Good growth; not many dead Very abundant-_-_-___ 
organisms present. 
Negative 
December 29, 1920. 
Numerous active | February 19, 1921. 
organisms. 
It was also evident in the cultures that Leptomonas ctenoce- 
phali seems to be less sensitive than Leishmania infantum as to 
changes in consistency of the medium, as no distinct deleterious 
effect was noticeable, particularly during the first days of the 
culture, by the use of varying amounts of either blood or agar. 
However, examination on February 19, 1921 (Table 4), some- 
thing over two and a half months after the inoculation, showed 
that there was still growth in the 2 per cent agar and 25 per 
cent blood medium, while the other blood combinations of the 
2 per cent agar yielded no growth at this time. 
To summarize: Strains of Leishmania infantum and Lepto- 
monas ctenocephali were used for cultivation experiments. Suc- 
cessful growth was obtained by using even a trace of blood 
provided the agar was very soft. The 2 per cent agar plus 25 
per cent blood and the 0.5 per cent agar plus 5 per cent blood 
combinations seem to offer optimal conditions for growth. 
I beg to acknowledge my gratitude to Professors E. E. Tyzzer 
and A. W. Sellards for the help they gave me while I was 
working in the laboratory of the Harvard School of Tropical 
Medicine. 
