360 Mr. Blackman and Miss Fraser. Sexuality and [Oct. 31, 



The structure of the mature apothecium is of the ordinary type ; there is a 

 definite parenchymatous peridium, a well-marked .hypothecium consisting of 

 large cells; and the paraphyses are large and club-shaped and filled with 

 orange granules (fig. 31). 



General Considerations. 



It is clear that the process of fusion in pairs of the female nuclei in the 

 ascogonium of Rumaria granulata must be considered as a reduced sexual 

 process which, in the absence of the antheridium, replaces the normal fertilisa- 

 tion by male nuclei such as we find in Sphcerotheca, Erysiphe, Pyronema, and 

 Boudiera. It renders even more untenable the most recent view of 

 Dangeard* (10) that in the Ascomycetes as a whole there is no fertilisation in 

 the ascogonium, but the sexual process has been shifted from that structure to 

 the asci; for in H. granulata we find that even in the absence of the 

 antheridium the process of nuclear fusion is not confined to the asci, but 

 there is an earlier fusion in the ascogonium, which must itself be considered 

 as the sexual process, although of a reduced type. 



As stated earlier, the question of the occurrence of an ordinary sexual 

 process in some at least of the Ascomycetes must now be considered as com- 

 pletely settled. Future work must decide how far the members of the group 

 exhibit ordinary sexuality or the reduced process described above ; it is possible 

 also that some forms are truly parthenogenetic,f while there appears to be no 

 doubt that others, as the Uxoascacece, are still further reduced, the asci having 

 a direct vegetative origin. 



It can hardly be denied that the process of fusion of the female nuclei in 

 pairs is derived by reduction from the ordinary sexual process such as we 

 find in Pyronema; therefore it seems best to class such a process as a 

 "reduced sexual process" (Blackman (5)), in which the male gamete has been 

 replaced by another female cell (nucleus), the aecidium, just as in Phragmidium 

 violaceum (5) the male cell is replaced by a vegetative cell. 



* Kuyper (21) in a recent paper, published since these observations were complete, has 

 come to a conclusion somewhat similar to that of Dangeard. He has investigated 

 Monascus and finds there only a single nuclear fusion, and that in the ascogonium, but 

 without relation to the male nuclei. He considers Monascus a primitive form and that 

 in the other Ascomycetes the fusion has been shifted to the ascus. Different results have 

 been obtained by other workers on Monascus, and Kuyper's figures are not very con- 

 vincing ; but if there is only a single fusion, such a fusion is obviously comparable to the 

 first fusion in Humana granulata and not to the second. 



t That is with potential female gametes developing without any process of cell or 

 nuclear fusion. If there be a true alternation of cytologically distinct generations in the 

 Ascomycetes this is not likely to occur, as true and complete parthenogenesis is unknown 

 in plants possessing such an alternation. 



