118 
Journal of Mycology 
[Vol. 11 
authors are really using quite different species. If some one 
were to collect all the effects ascribed to Penicillium glaucum 
he would be convinced that it was the most versatile organism 
on earth. But a considerable acquaintance with green Penicil- 
liums leads to the reply that the real organisms involved would 
make a most motley collection. 
In the first place it is perhaps needless to say that most 
dairy fungi are cosmopolitan saprophytic species. In addition 
to these any saprophyte or even parasite capable of growing 
in milk or common culture media may be found there at times. 
Although this latter group may be numerous at a particular time 
and place they are comparatively easily distinguished from that 
special lot of species which are almost universal in dairy cul¬ 
tures. Here we encounter a great difficulty. Mycological liter¬ 
ature is full of descriptions of saprophytes such as Penicillium, 
Cladosporium, Aspergillus, Fusarium, Alternaria, and worse still 
Monilia and Oospora (Oidium) in which brief notes upon a 
single colony of fungus upon a named substratum are the only 
basis for identification. In these one feels fortunate when he 
finds a spore measurement. Too commonly the substratum 
named is either unique or very vaguely defined, while the sug¬ 
gestion of culture is a rarity. Satisfactory identification a 
second time by another worker might occur, but only accident¬ 
ally. 
Dr. Fr. Dierckx in speaking of the genus Penicillium (trans¬ 
lating freely), says, “For the genus Penicillium it is only ex¬ 
ceptionally possible to identify a type met by accident upon acci¬ 
dental substratum, without cultivation. In fact the molds vary 
immensely according to the circumstances under which they are 
observed.” He continues saying that in such a genus the only 
hope for stable identification is in culture for several generations 
under “rigorously uniform conditions.” 
This paper attempts to present a plan for obtaining more 
definite knowledge of these forms by the dairy student in the 
use of his own methods. The media used have been the nutrient 
agar and peptone milk-sugar-gelatine described by. Conn (Bact. 
in Milk and its Products p. 253, 268) in addition to ordinary 
potato agar and potato plugs. Special experiments have involved 
many other media. These cultures were commonly acidified by 
two to five drops of normal lactic acid to exclude bacterial 
growth. Once freed from bacteria the fungi were studied in 
both acid and neutral media. 
It is useless to say that any classification of such forms as 
Penicillium and Aspergillus, to be of value, must rest upon ascus 
formation. The discovery of such fruit or methods of inducing 
its formation in particular species is of much interest, but since 
the vast majority of the species concerned have failed to pro¬ 
duce asci under stress of thousands of cultures by numberless 
