258 THE AMERICAN NATURALIST. [Vol. XXXIX. 



by treating the material with chloral hydrate so that no walls 

 were formed between the daughter nuclei, which remained in 

 the common mother cell and presently fused with one another. 

 The fusion nucleus presented a double number of chromosomes 

 (twice that of the normal sporophyte) in succeeding mitoses 

 which became reduced in a few hours so that later divisions 

 showed the number characteristic of the sporophyte. Nemec 

 regards nuclear fusions and reduction phenomena as self regulat- 

 ing processes which follow the vital cell fusions characteristic of 

 fertilization. The latter (cell fusions) are then the essential 

 phenomena of sex and nuclear activities follow automatically. 

 Reduction phenomena are atavistic in character. Nemec con- 

 siders these results in serious conflict with Strasburger's ('94) 

 theory of the periodic reduction of the chromosomes, believing 

 that the number of chromosomes is not so likely to give the 

 characters of the respective sporophyte and gametophyte gener- 

 ations as other factors. 



Nemec's contribution is chiefly of interest to us in the present 

 connection as showing that nuclear fusions may result from dis- 

 turbances of the normal environment very far removed from the 

 conditions that produce sexual cells. And this emphasizes our 

 contention that sexual processes must be judged through phylo- 

 genetic analysis and not by physiological resemblances. Thus 

 the nuclear fusions in the ascus, in the basidium, preceding apog- 

 amous development of the fern, and perhaps the union of polar 

 nuclei in the embryo sac may be involved with special physio- 

 logical conditions although they resemble outwardly sexual 

 processes and are sometimes a substitute for these. But never- 

 theless they are asexual , nuclear fusions lacking that funda- 

 mental character of sexuality, the result of sexual evolution, 

 namely, a fixed position in a life cycle established by phylogeny 

 and expressed by the classic phrase " ontogeny repeats phylog- 

 eny." They are departures from the noi^mal life history either 

 apogamous in character or concerned with some other peculiarity 

 of the plants' existence. 



