20, 2 Leiva: Cultivation of Leishmania infantum 181 
. 
quirements for growth of these parasitic flagellates. Each of the 
two variables, namely, the amounts of agar-agar and of blood, 
as important constituents of the medium, has its own effect on 
their continued life. 
TABLE 2.—Leishmania infantum grown in 2 per cent agar plus different 
percentages of defibrinated rabbit’s blood. Cultures inoculated Decem- 
ber 1, 1920. 
5 per cent blood. 10 per cent blood. | 25 per cent blood. |Date of examination. 
Very few active organisms _____ Very few active | Very few active | December 2, 1920. 
organisms. organisms. 
Do A rar gee ciinge Pi se do .---| Good growth ____._. December 8, 1920. 
Abundant growth ....___.______ Abundant growth__| Very abundant | December 6, 1920. 
growth. 
Only trace of a few living or- | Good growth -...... Numerous active | December 11, 1920. 
ganisms, Many dead indi- organisms; very 
viduals. good growth. 
Still a few living organisms _._.| Numerous organ- | Very numerous or- | December 17, 1920. 
. isms, ganisms. Isolat- 
ed ones and also 
in clumps. 
Many dead organisms___________ Good growth _..-___ Very numerous_-_..-| December 29, 1920. 
Sb: ESR epee dial Negative. .......-_- Many granulated | February 6, 1921. 
and degenerating : 
forms. Some ac- 
tive. 
TABLE 3.—Leptomonas ctenocephali grown in 0.5 per cent agar plus dif- 
ferent percentages of defibrinated rabbit’s blood. Cultures inoculated 
December 1, 1920. 
5 per cent blood. 10 per cent blood. | 25 percent blood. {Date of examination. 
A few live organisms___________ A few live organ- | A few live organ- | December 2, 1920. 
isms. isms, 
eee cobtunt BE a ee Good growth ..----- Good growth -.__._. December 3, 1920. 
Very good growth........______ Very good growth..| Very good growth..| December 6, 1920. 
Mumbo oo. Numerous.._.....--. Very numerous, | December 11, 1920, 
j many rosettes. 
PO eg CEE PS ee TA Very numerous.--.. December 17, 1920. 
Numerous; many dead organ- | Numerous; many do December 29, 1920. 
isms, dead organisms. 
a 
The addition of blood to the medium proved to be of distinct 
advantage and almost an essential in the hands of previous 
Workers. However, it seems that consistency of the medium as 
a whole exerts no little influence. For instance, the writer got 
Just as good results when using 0.5 per cent agar with 5 per cent 
blood as when he employed 2 per cent agar with 25 per cent 
