310 The Botanical Gazette. [July, 
over the surface of previously solidified agar in the plate, thus 
securing numbers of spores in a thin plane at the surface of 
the medium. On the following morning eighteen hours after 
of spores was selected for a photomicrograph (fig. 11), con- 
taining three spores with young germ tubes and two spores 
not yet germinated. One of the spores germinating shows 
plainly the division of the spore into two cells at the time. 
Twenty-four hours later considerable growth had taken place. 
The preceding day when the first photomicrograph was taken, 
a cover glass was placed over a portion of the culture in or- 
der to prevent the moisture from the surface of the agar from 
condensing on the objective when the strong reflected rays of 
the sun should be mirrored through the culture during the 
exposure. 
From former experiences it was found that very little growth 
was made after having once shut out the access of oxygen by 
placing a cover glass over a number of the spores. In this 
case the growth was surprising for it was quite considerable, 
though not so much as that of spores not thus covered. Per- 
haps this considerable growth compared with the very little 
or none in other experiences was due to the peculiar way in 
which this culture was made. A photomicrograph of the 
growth of one spore was made at this time (forty-two hours 
after sowing) and is shown in fig. 12. The spore itself at the 
center of the colony can be seen from its greater diameter 
than that of any of the threads. It is also quite strongly 
constricted at the center which is brought about by the rapid 
enlargement or swelling of the spore. In order to bring cer- 
tain of the threads into strong focus which it was desired to 
reproduce with their characteristic features in detail the spore 
was thrown slightly out of focal plane, and the septum in the 
spore is not well seen and the vacuoles not distinct. In certain 
