MORPHOLOGY AND LIFE HISTORY OF SOME ASCOMYCETES 439 
PI. XXX) by some such substance; and, when wet, they spread out over 
the surface of the leaf. 
Spermatia continue to develop until about the middle of December. 
At this time the spermogonium is a globose or conical structure with a very 
thin wall composed of two or three cell layers. There is a small pore, but 
no beak, at the apex. The cells which make up the wall of the spermo- 
gonium are thick-walled and brown, and are readily differentiated from the 
thin-walled and colorless spermatiferous cells. 
Text Fig. 2. Stages in the development of the spermatiferous cells and the spermatia : 
a, spermatiferous cell just before the first nuclear division; b, just before the second nuclear 
division; c, just after the formation of the young spermatia, the fourth spermatium being 
beneath the three shown; d, single sterigma and four young spermatia showing within the 
mother cell wall; e, two sterigmata formed by one mother cell; /, g, spermatia passing 
through sterigmata; h, mature spermatium, showing large nucleus almost filled by the 
nucleolus. All drawn with the aid of a camera lucida. X 4200. 
Perithecia. The perithecia begin their development coincidentally with 
that of the spermogonia, or perhaps a few days later; and in the early 
stages it is not possible to say which are spermogonial and which perithecial 
primordia. Very soon, however, they may be differentiated by means of 
the changes which occur in the cells that make up the weft. In the young 
spermogonium the spermatiferous cells begin to develop; while in the center 
of the young perithecium the carpogonium, a single filament, becomes very 
conspicuous in stained material because of its great affinity for protoplasmic 
stains. Occasionally two carpogonia develop in a single perithecium. 
The carpogonium arises from the base of the young perithecium; and 
