150 
ANNALES DE L’INSTITUT PASTEUR 
authorities give of the thrush fungus, some stating that it 
liquéfiés gélatine, others affirming the reverse ; some vvriters 
giving it as clotting milk : others as having no action on this 
medium. ïïow could the same species présent sucli widely 
differing characters? 
During my work on the suhject in London, ail swabs sont to 
the Lister Institute for examination, taken from cases of thrush 
stomatitis, were kindly handed to me. Each swab was 
smeared on two maltose and two glucose agar plates, and every 
colony of fungi was investigated in the same manner as I had 
investigated the thrush found in the tropics, viz. h y passing 
them through a numher of sugar hroths, and growing them on 
milk gélatine, and sérum. It seems to me that the classifica¬ 
tion of fungi of the généra monilia , saccharomyces , and cmjpto - 
coccus , cannot be based purely on lheir morphology ; their 
biochemical characters should be studied, and whenever 
possible, their biological properties, such as productions ot 
agglutinins, etc. in inoculated animais, 
The most important biochemical properties are put in 
evidence by growing the fungi in milk, gélatine, and various 
sugar broth. À large numher of sugars should be used in the 
same manner as is done in the classification of the various 
species of intestinal bacteria. It is to be noted that the reac¬ 
tions with certain sugars are constant, while with others, for 
instance mannite, may vary. It is to be noted also that in 
analogy to intestinal bacteria, a species may be trained to 
ferment certain sugars in which it did not act when recently 
isolated. While taking ail this into account, I believe the 
investigation of the various biochemical reactions to be of the 
greatesl value for classifying lhese fungi. 
In London, from 11 cases of thrush, seven different species 
of fungi belonging to lhe genus monilia were isolated. The 
characteristics of each species are collected in the following 
Table : 
Morphologically ail the fungi had the characters of those 
belonging to the genus monilia. None belonged to the genus 
endomyces , no endospores and asci having been seen. They 
ail grew abundantly on the various sugar agars, especially 
if slightly acid, less abundantly on ordinary agar. On solid 
