SEXUAL REPRODUCTION 97 



be admitted is concise and logical, and may possibly 

 represent a new conception of sexuality intended eventually 

 to replace the more primitive form, which, as already stated, 

 is undoubtedly on the decline. 



Although the origin of the ascus from the binucleate, 

 penultimate cell of an ascogenous hypha is very frequent, 

 it is not constant, as indicated by Faull, who has quite 

 recently investigated the subject, and summarises his 

 observations as follows : 



1. The asci bud out from the penultimate cells of the 

 ascogenous hyphae in some forms, in others from the 

 terminal cells, and in a few species apparently from any 

 cell. 



2. In every case that was definitely determined, the 

 uninucleated stage is preceded by a fusion of two nuclei 

 within the ascus. The conjugating elements, though not 

 sisters, may sometimes be the daughters of sister nuclei. 



3. The age and development of the asci at the time of 

 fusion vary considerably in different species, and to some 

 extent, though within narrower limits, in the same plant. 



Barker, Ann. Bot., 17, p. 167 (1903). 



Blackman, Ann. Bot., 18, p. 324 (1904). 



Dangeard, Z<? Botaniste, ser. 7, p. 89 (1900). 



De Bary, Ann. Sd. Nat., ser. 4, n, p. 236 (1860). 



toi&M t Priogsh. Jahrb., 30, p. 285 (1897). 



Fisch, Bot. Centr., 24, p. 221. 



Griiber, Ber. d. deutsch. Bot. Ges., 19, p. 51 (1901). 



Harper, Ann. Bot., 14, p. 321 (1900). 



Juel, Flora, 91, p. 47 (i9 02 )- 



Leger, Recher. Struct. Mucor., 1896. 



Sappin-Trouffy, Le Botaniste, ser. 5, p. 59. 



G 



