EUASCOMYCETES 183 



the A. herbariorum-repens group, the antheridium is still more retarded 

 and may only function when the ascogonium is already septate. Occa- 

 sionally it may be entirely absent. In other forms, as A. flavus and A. 

 fumigatus, the antheridium is entirely suppressed and the formation of 

 fructifications proceeds only from the ascogonial helix. In a fourth 

 stage, in Penicilliopsis clavariaeformis, the ascogonia are probably no 

 longer formed and the development of the ascogenous hyphae takes place 

 pseudogamously. These two important facts, that all these types occur 

 so close together and that the different forms are often variable in behav- 

 ior, allow one to conclude that the reduction of sexuality is still recent 

 and has not yet become stabilized. 



Fig. 115. — Penicilliopsis clavariwformis. Left, coremia; right, young fundament of fructi- 

 fication; center, half-mature fructification. (Natural size.) 



According to the further fate of the fructification fundaments in the 

 Aspergillaceae group, two types may be distinguished. In the first type, 

 to which belong the majority of the above forms, as A. herbariorum, A. 

 fumigatus, Penicillium vermiculatum and Acauliumalbonigrescens, the asco- 

 genous hyphae divide without resting periods into binucleate cells which, 

 with fusion of their nuclei, swell to asci. They gradually dissolve the 

 inner layers of the fructification parenchyma and thus provide the mate- 

 rial for the nourishment of the maturing ascospores. At maturity the 

 perithecia consist of a more or less solid pseudoparenchymatous sheath 

 which is filled with a brownish spore powder and generally opens at the 

 top by the decay of the cover. In Aspergillus nidulans, the fructifications 

 do not arise free on the mycelial mat but are embedded in peculiar bladder- 

 like sheaths (Fig. 116, 3). These are formed because the neighboring 

 hyphae next the mycelial cover do not branch further, and the end cells 



