APOGAMY, APOSPORY, AND PARTHENOGENESIS 



313 



id) There is no female organ : fusion takes place bet ween i wo adjacent 

 tissue-cells of the gametophyte; the sporophyte is developed from 

 diploid cells ["grafted tissue"] thus produced, but there is no 

 proper zygote as there is in a, &, and c: observed I Farmer [and 

 Digby] L907) in the prothallium of certain ferns I Lastrcea p«< udo- 

 mas, var. polydactyla) [Fig. L24, A]: male organs (and sometimes 

 female) present l)in functionless. Another such case is thai 

 of Humaria rutilans (ascomycete), in which nuclear fusion 



m^AJ'n J *</'■■■/ 



Fig. l-'.".. 

 ,1, cell fusion in the sporangium of Aspidium falcatum. > 1950. I B. ^- 4 Z/ ™ 

 1911 ) B, incomplete nuclear division in sporangium ol Nephrodium htrtijx ■ \-> ■ 



(After Steil 1919.) C, apogamy and sporophytic budding in the embryo sac o I Ua 



pastorates: egg developing apogamously below; cell of aucellus forming an embryo above; 

 two polar nuclei and one synergid nucleus al center. [After Murbeck, IWJ 



has been observed (Fraser L908) in hyphse of the hypothecium: 

 the asci are developed from these hypha, and in them meiosis 



takes place; there are no sexual organs. [A similar condition 

 has been reported in Helvetia crisp*, (Carruthers L911) and 

 Polystigma rubrum (Blackman and Welsford 1912). It has 

 already been pointed out (p. 291) that many students of the 

 ascomycetes deny the existence of a nuclear fusion in the 

 archicarp or vegetative cells, holding rather that the only 



