The Origin and Development of the Apothecium etc. 
411 
formed, in each swelling of which is a single nucleus. Darbishire says 
that it appears that after fertilization no more cross walls are formed. 
This last is in agreement with my observations on Collema pulposum. 
However, I liave found that any part of the ascogone which represents 
one of the original cells may contain several nuclei, also that the number 
varies considerably. Where I have found but one nucleus, as in Figure 50, 
PI. XXXIV, at c, I have taken it to be the primary nucleus of that cell, 
which for some reason had not received the Stimulus to division. Stahl 
also observed that as the apothecium Anlage increases in size, the ascogone 
comes to have more cells as a resiüt of intercalary growth. Stahl says 
nothing of a breaking dow r n of the cross walls in the ascogone. But it is 
likely that with unstained preparations these openings are not so evident. 
Besides, here, as Baur observed in C. crispum, the structure is obscured 
by the surrounding thick growth of vegetative liyphae. In Anaptychia 
ciliaris (Baur, 5), the apothecium arises from two or three ascogones 
which are not so soon covered by vegetative liyphae. The cells of the 
ascogone increase greatly in size and they are connected by broad plasma 
bands. There appears to be no increase in the number of cells by inter- 
calary divisions. 
Ascogenous and sterile hyphae in the apothecium. 
In Anaptychia many cells of the ascogone (but not all) branch to 
give rise to the ascogenous hyphae. As a result of this branching, the 
ascogone cells become cpiite empty and later eompletely disappear. The 
ascogenous hyphae are thinner walled and stain differently from the 
vegetative hyphae which inake up the sheath around the ascogone. The 
cells are very irregulär in form. In Pertusaria communis (Baur, 4), the 
cells of the ascogenous hyphae are very irregulär in form and are uni- 
nucleate, with granulär, much vacuolated cytoplasm. In Collema crispum, 
also, Baur (3) found that the cells of the ascogenous hyphae are uni- 
nucleate. In C. microphyllum, Stahl describes the hyphae as septate, 
the cells varying greatly in size and shape — broad cells alternating with 
narrow ones and often the same cell much expanded at one end and nar- 
rowed to a filament at the otlier end. The content of these cells is like 
that of the ascogone cells, homogeneous and finely granulär. In C. pul- 
posum I have found considerable Variation in the size of the cells of the 
ascogenous hyphae and also in the content. 1 find that there may be 
one or several nuclei; there is little cytoplasm, and what there is is less 
granulär and stains differently from that of the hyphae from which the 
paraphyses arise. There is less cytoplasm in the basal cells nearest the 
