ASCOMYCETES AND BASIDIOMYCETES. 77 



It is especially of interest that Miss Nichols finds binucleated cells regu- 

 larly present in the rhizomorphs of a large number of widely separated 

 genera. 



The observations of Miss Nichols and those of Blackman and 

 Christman do not make it any easier to assume a phylogenetic relation- 

 ship between Ascomycetes and Basidiomycetes. It is highly probable 

 that such resemblances as exist between the ascocarp and the carpophore 

 are due to the duplication of unrelated forms under similar develop- 

 mental conditions, which occurs at many other points in the plant king- 

 dom. While a conjugation of gametes is present in the secidium, it is 

 still plain, from the existence of the now functionless spermatia, that 

 the present sexual fusions are highly modified processes which have 

 returned in the character of the gamete to something like a zygosporic 

 type from what originally was doubtless a true carposporic method of 

 reproduction. There is no evidence of any such modification in the 

 sexual apparatus of the Ascomycetes, and in them also there is at most 

 only the beginning of the long series of regularly binucleated cells which 

 characterize the rusts and Basidiomycetes. Still, the fusion in the 

 basidium may have had an origin similar to that suggested above for 

 the fusion in the ascus, and, combined with conjugate division, may 

 gradually have led to the apogamous condition which, it seems probable, 

 is found in the Basidiomycetes. The rusts on this hypothesis represent 

 a condition when conjugate division has worked back, in the life history 

 of the sporophyte, to the stage of fusion of the gametes, thus replacing 

 the nuclear fusion in the &^% which must probably be assumed to have 

 occurred in some more primitive type from which the rusts have devel- 

 oped. If this more primitive type was, as Blackman believes, one of 

 the red algae, we must probably consider that two diverging series of 

 fungi, the Ascomycetes and the Basidiomycetes, had their origins in 

 this group. 



As has been many times noted, one of the commonest grounds for 

 the assumption of a relationship between Ascomycetes and Basidio- 

 mycetes and the relationship of these groups to the Florideae lies in the 

 generally suggested physiological parallelism between ascocarps, carpo- 

 phores, and cystocarps with each other and with the sporogonium of 

 the liverwort and moss. A functional resemblance between the struc- 

 tures in question is apparent, and Wolf (99) has described a reduction 

 of the number of chromosomes in connection with the formation of the 

 carpospores in Nemalion. The evidence, however, on which he bases 

 his conclusion is not very convincing. Such comparisons also still 

 leave the nature of the tetraspores and the occurrence of specialized 



