Vol. 36 



No 10 



BULLETIN 



OF THE 



TORREY BOTANICAL CLUB 



OCTOBER, 1909 



The development of the imbedded antheridium in Dryopteris stipu- 



aris (Willd.) Maxon and " Nephrodium molle"* 



Caroline A. Black 



(WITH PLATES 26-28) 



The discovery by Farmer and Digby ('07) of the development 

 of a sporophyte from the essential fusion of two vegetative cells of 

 the gametophyte has aroused a keen interest in the study of apog- 

 amy in ferns and other higher plants as well, and has given a 

 somewhat different meaning to the already variously interpreted 

 term, apogamy. 



These authors have found that in the prothallia of Lastrea 

 pseudo-mas^ van polydactyla Dadds, and Lastrea psettdo-mas^ van 

 polydactyla Wills, developed from normal spores and therefore pos- 

 sessing the gametophytic number of chromosomes, a doubling of 

 the chromosomes was secured in an apogamous embryo by the 

 migration and fusion of vegetative nuclei. The region of migrat- 

 ing nuclei, while not confined to a definite area on a prothallium, 

 was always found to be in the younger portions. The basis of the 

 entire process of the migration and fusion of nuclei was observed 

 to be chemotactic. The elongated migrating nucleus coming in 

 contact with the wall of the receptive cell was seen to slip through 

 an opening, made, probably, by a fermentative action, and fuse with 

 the nucleus of the invaded cell directly or after some time. It is 



I 



believed by Farmer and Digby that this fusion of the nuclei of 

 adjacent vegetative cells, accompanied by the doubling of the 



-> 



'^^ Nephrodiiim moUe^ according to Christensen (Index Filicum 444. 1905), is a syn- 

 onym of Dryopteris parasitica, 



[The Bulletin for September, 1909 (36 : 489-556) was issued i O 1909.] 



567 



