Oidium Lactis. 



Origin. — Almost invariably present in milk and in but- 

 ter; also in sugar solutions of various kinds, and in brewer's 

 yeast. 



Form. — A delicate, white mycelium of forked, wavy 

 threads. No special fruit-organ is present. The conidia 

 or spores are very irregular in size .and form; they may be 

 oblong, round or oval. 



Anilin dyes. — React readily. The specimen shrinks on 

 drying. 



Growth. — Is rapid, especially on acid media. 



. Gelatf,n plates. — Delicate white stars form, which rapidly enlarge, 

 and spread on the surface as dry, flat, whitish masses. Under the 

 microscope the colonies show radiating, branched hyphK and chains 

 of conidia. 



Stab cultwre. — Growth takes place along the entire line of inocu- 

 lation, and is most abundant at or near the surface. A branching 

 network of threads extends outward into the solid gelatin. On the 

 surface a grayish white, dry, low growth forms. In old cultures only 

 the upper layer of gelatin shows the radiating lines. 



Streak culture. — On agar, it forms a grayish white, thin growth. 



Milk. — Growth occurs without altering the composition. 



Temperature. — Grows best at ordinary temperature. 

 It can grow in the incubator. 



Behavior to gelatin. — Does not liquefy. 



Pathogenesis.— It has no effect on animals. A some- 

 what similar organism, the Oidium Tuckeri, produces a 



vine disease. . 



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