322 Harper.—Sexual Reproduction in Pyronema 
present. This is a remarkable condition, assuming that 
ascogenous hyphae are only modifications of those that form 
the vegetative thallus. It would be expected that they 
might bud off at any time from the vegetative hyphae, and 
in such positions as would be most convenient for the 
development of asci in the hymenium. Krabbe further 
describes the ascogenous hyphae in the podetium-stalks as 
densely staining mycelial branches richly stored with food- 
materials such as glycogen. He also distinguishes them by 
the fact that their walls stain blue with iodine, as had been 
earlier observed by Schwendener. 
Still, I am of the opinion that it is a question whether these 
densely filled hyphae are really the ascogenous hyphae. In 
Ascofrolus, Peziza Stevensoniana , Pyronema , and other forms, 
the ascogenous hyphae are always empty and frequently 
collapsed in mature fruits, while the branches destined to 
produce paraphyses, which are to be developed for the 
continued growth of the hymenium, agree in their general 
appearance with Krabbe’s description of the ascogenous 
hyphae. I was myself misled for a time by these late- 
developing vegetative branches, their prominence and abun¬ 
dant contents leading naturally to the assumption that they 
were destined to develop asci. As a matter of fact, however, 
the asci depend very little on food brought by the ascogenous 
hyphae, which contain little but nuclei, except perhaps at their 
very tips. If Krabbe’s densely staining hyphae are really 
vegetative, he would very naturally be led to the conclusion 
that asci and paraphyses are parts of a common system of 
mycelial branches, since he would readily find paraphyses 
arising from these densely stained hyphae, and his precon¬ 
ception that they were the ascogenous hyphae would naturally 
bias his judgement in determining the difficult question as to 
their actual connexion with the asci. 
This possible mistake of Krabbe’s is worth such full con¬ 
sideration, since other students are likely to be led into the 
error of expecting that the ascus-bearing hyphae will be more 
conspicuous and more densely filled with protoplasm than 
