HYPOCREALES 227 



hyphae in the usual manner. The perithecia are gregarious or scattered, 

 smooth or with loose hairs, the cavity lysigenic, rilled at first with parallel 

 septate hyphae which disappear as the young asci expand ; the ascospores 

 become black or greenish black and longitudinally ribbed. N. erythraea 

 is apparently homothallic, while N. sitophila and N. crassa are hetero- 

 thallic (Shear and B. 0. Dodge, 1927). In N. tetrasperma, the spores 

 vary much in size depending upon the number produced in an ascus. 

 Ordinarily there are four spores, but occasionally five to six or two to 

 three are produced. Cultures from the large spores are homothallic, 

 while those from the small spores are heterothallic. The spindle of the 

 first division in the ascus lies along the long axis, hence the daughter 

 nuclei migrate toward the ends of the ascus. In the second division, the 

 spindles are longitudinal or in about half the cases, oblique and appear 

 to be dividing conjugately, hence the nuclei finally appearing at the ends 

 of the ascus are non-sister nuclei. In the third division, the spindles are 

 transverse and the adjacent non-sister nuclei unite in cutting out a large 

 homothallic spore. This is followed by subsequent slipping and turning 

 of the spores, since at maturity they lie in a single row. In the uninucle- 

 ate heterothallic spores, the relations of the spore nuclei are not clear, but 

 in N. crassa and N. sitophila, the adjacent, uninucleate spores are always 

 developed from sister nuclei (B. 0. Dodge, 1927). In these species, 

 where there is little chance for shifting, further studies by B. O. Dodge 

 and Wilcox will probably locate conclusively in which division of the 

 ascus the segregation of sex occurs. 



Peckiella is parasitic on pileate fungi and morphologically corre- 

 sponds to Hypomyces of the Didymosporae; only their ascospores are 

 unicellular. On the under side of caps of Lactarius deliciosus, P. lateritia 

 forms a stroma thick enough to cover the lamellae. As in P. Thiryana 

 (Maire, 1905), which has also been investigated in this respect, the hyphal 

 cells are uninucleate. As in Melanospora Mangini and Neurospora 

 erythraea, only the ascogonium is formed. It curls twice at the most. 

 Its cells undergo repeated divisions but always remain uninucleate. 

 Later, by nuclear divisions which are not followed by septum formation, 

 they become binucleate and develop to ascogenous hyphae which form 

 asci according to the hook type (Moreau, 1914). 



Neocosmospora vasinfecta will only be mentioned here because it is 

 erroneously considered the cause of a wilt of cotton and of watermelons 

 and is occasionally described as such in the literature of plant pathology. 

 Its perithecia, like those of the simpler species of Melanospora, arise singly 

 on the substrate and are colored a brilliant red (Butler, 1910). 



The second stage, in which the perithecia are united on undiffer- 

 entiated pulvinate stromata, is shown by Entonaema and Polystigma. 

 As Polystigma is known cytologically and hence affords opportunity 

 for a special discussion, we will return to it at the end of the Amerosporae 



