Di2 STORRS AGRICULTURAL EXPERIMENT STATION. 
may be produced at each end of every cell, or several at each 
end, and these branch indefinitely. The fruiting branches are 
mostly produced as outgrowths from the distal ends of the cells. 
These extend upward into the air or remain entirely submerged 
in many cases. From the ends of these outgrowths one to 
several rows of oblong or cylindrical cells begin to be pinched 
off. If extending above the surface this gives rise to chains 
of delicate shimmering cells which appear as a powdery cover- 
ing upon the surface, which can be seen with a good lens to be 
arranged into chains. In some strains of Oidium all of these 
chains (and some of the chains in all strains) of spores remain 
submerged and germinate at once, so that they give rise to 
unintelligible mats of hyphae. Oidium produces a very slight 
acid reaction to litmus at first, then a strong and continued 
alkaline reaction. It liquefies sugar gelatine under the colonies, 
but does not extend the area of liquefaction beyond the edge 
of the colony. Oidium always and everywhere tested has 
produced a strong and very characteristic odor. Once familiar 
with this odor the worker may recognize it anywhere. © Its 
spores or oidia are hyaline, smooth, cylindrical, 3.5-5 by 6-30, 
varying with the conditions and the substratum and perhaps 
at times exceeding these limits. These swell variously and 
germinate in many ways so that no germination characters 
are definite. Upon some media this mold may be induced to 
produce a large growth of aerial mycelium, but the limits here 
defined will include the variations to be found upon the usual 
culture media. | 
Oidium lactis is described as universally present on milk and 
its products. Epstein even suggests that experiments upon 
milk and cheese can not be freed from its presence without 
sterilizing. The same or almost indistinguishable forms are 
found upon decaying vegetables and fruits, which may give 
reason for the statement that the odor produced by Oidium is 
that of rotten cabbage. There seems to be good reason for 
saying that all these forms are but varieties or strains of the 
same species. Comparison of several of them shows that under 
uniform conditions the morphology of all these forms is very 
nearly the same. This is also largely true of their physio- 
logical effects. ‘This mold has been much studied and numerous 
papers discuss its nature and physiological effects as well as its 
