182 COMPARATIVE MORPHOLOGY OF FUNGI 



and, if Dangeard observed the normal development, its single nucleus 

 is functionless. 



The behavior of the third stage will be described for the best-known 

 Aspergillus herbariorum-repens group. (For A. herbariorum, by investi- 

 gations of Fraser and Chambers, 1907, and Dangeard, 1907, and for A. 

 repens, a small variety of A. herbariorum, by the investigations of Dale, 

 1909 and Moreau, 1913). As a branch of a hypha, there arises an 

 ascogonium, which coils in a helix with a continually shortening radius. 

 It is divided by one or more septa in two or more multinucleate cells of 

 which the terminal is generally the longest and contains up to 20 nuclei. 

 Shortly before or after septation of the ascogonium, the antheridium 

 appears and climbs along the ascogonial helix (Fig. 114, B, C). Many 

 times it is formed independently of the ascogonium, on another hypha, 

 often it grows from two or three slender branches on the basal, more 

 rarely from a higher coil of the ascogonium; occasionally it may arise 

 from the interior of the helix and thereby attain the same aspect as in 

 A phanoascus and Ctenomyces. An open communication between antherid- 

 ium and ascogonium was not demonstrated in any case. The antherid- 

 ium appears to be rudimentary; the nuclei often degenerate before it 

 has reached its full length, or it ceases its growth half way and does not 

 reach the tip of the ascogonial spiral; or it may be entirely absent. In all 

 these cases, with or without the antheridium, the ascogonium develops 

 parthenogenetically; it divides into binucleate cells some of which grow 

 to ramose ascogenous hyphae. 



Thus the third stage is characterized by the functional degeneration of 

 the antheridium, which may be formed only when the ascogonium has 

 completed the portion of the cycle in which fertilization would be possible 

 and has already entered upon a stage of septation. 



In the fourth group, as in Aspergillus flavus, A. fumigatus and A. 

 Fischeri (Dangeard, 1907; Domaradsky, 1908), the antheridium is no 

 longer formed. Only one helical ascogonium is formed which divides into 

 binucleate cells and develops ascogenous hyphae in the usual way. 



In a fifth group, as in Penicilliopsis clavariaeformis, as far as previous 

 observations of the author extend, the formation of the fructification is 

 no longer introduced by the formation of an ascogonium. Conidiophoric 

 coremia radiate laterally or teminally without apparent reason (Fig. 

 115, 2, outer right) and change into perithecia in a still unknown manner. 



Apparently there has taken place in the Aspergillaceae a gradual 

 degeneration of sexuality, because of the retardation in the formation of 

 the antheridium. The Penicillium "crustaceum" group is apparently 

 still potent sexually; it may be directly connected to Gymnoascus Reesii. 

 In other forms, as P. vermiculatum, the antheridium is formed when the 

 ascogonium has already become multinucleate and hence may no longer 

 be fertilized by the uninucleate antheridium. In still other forms, as in 



