Dec. 1898.] BOTANICAL SOCIETY OF EDINBURGH 139 



asci on indifferent liyphtc of lower Ascomycetes may be 

 due merely to the apogamic production of each young ascus 

 which represents a single individual. 



FLORlDEiE. — If the view here put forward as to the 

 significance of these nuclear fusions in Fungi and Angio- 

 sperms be correct, it might be anticipated that similar 

 unions would occur in other great classes of plants, in 

 forms possessing a small fructificative generation, and 

 exhibiting alternation of generations. So far as I know, 

 only one family of algic — the Floridea? — provides appro- 

 priate examples that have been investigated. And it would 

 be a strong confirmation of my hypothesis if in the 

 Floridese there occurred definite nuclear unions not repre- 

 senting the coalescence of the nuclei of the male and 

 female cells. Such nuclear unions might occur in con- 

 nection with the inception of the parasitic and fructificative 

 sporophyte. Schmitz stated that, in a number of Floridete, 

 not only do the ooblastema-cells unite M'ith auxiliary cells, 

 but definite nuclear fusions also ensue before the production 

 of the carpospores. Comparing this case with these already 

 discussed, it would be natural to conclude that the sporo- 

 genous portion of the cystocarp, representing a small 

 fructificative sporophyte, is a degenerate form, and that 

 the alternation of generations in this family is homologous. 

 Aud, comparing the Florideic with the Ascomycetes, it 

 is evident that the gradual evolution of tlie cystocarp has 

 proceeded along lines which are perfectly paralleled by those 

 along which the ascocarp has advanced. Oltmanns (7) 

 has, however, recently denied the occurrence of any nuclear 

 fusions in the Floridea? other than that in the actual 

 sexual act. 



The remarks contained in the preceding paragraphs 

 serve to show that the peculiar nuclear fusions taking 

 place in the Ustilaginete, Uredinese, Basidiomycetes, Asco- 

 mycetes, possibly in the Floridea?, and in the Angiosperm?e, 

 show strong physiological and morphological analogies to 

 sexual unions. That there is no homology between the 

 latter and the former is clearly shown in the Angiosperms, 

 Floridese (?), and probably in the Ascomycetes ; for, in 

 these classes, the nuclear fusion in question does not take 

 place at the same stage in the life-history as did the sexual 



