BETTS : THE FUNGI OF THE BEE-HIVE. 159 
In others, however, it deepens to a dull mustard colour, olive-yellow, 
or (in many cases) a deep brown (almost black). The torulose hyphae 
undergo this change as well as the conidia. 
The alteration in colour is accompanied by a progressive altera- 
tion in the chemical constitution of the cell-walls. Young conidia 
(that is, from white or light yellow cultures) are dissolved in sul- 
phuric acid, often without the application of heat. After a culture has 
reached the dull mustard-yellow or light olive stage, however, the 
conidia are not destroyed by heating in sulphuric acid. Similar 
results are obtained with hydrochloric acid, except that the young 
conidia do not entirely disappear even on heating, but traces of them 
remain. Caustic potash solution does not appear to produce any 
marked effect on the conidia at any stage. 
Fig. 28.—Oospora favorum. Conidiophore. x 640. 
This species appears to be variable. I cultivated two varieties, 
derived originally from the same culture. One of these tended to 
colour and cuticularize earlier than the other, and to attain ultimately 
a darker colour. They were transferred to various media, and in 
nearly every case the difference referred to was apparent. 
The results of the temperature-experiments were somewhat con- 
tradictory, and no certain conclusions can be drawn from them. The 
fungus did well at room temperature in all cases. 
This species appears to do best on pollen; cultures on honey 
media were, however, fairly successful. Normal conidia were pro- 
duced on fairly dry potato, in small quantity. On prune decoction 
media the growth is torulose. Gelatine is liquefied. From the results 
of cultures on litmus media it appears that acid is occasionally 
produced. 
