﻿VOLUME XXXV 



NUMBER 4 



Botanical Gazette 



APRIL, igoj 



OOGENESIS IN SAPROLEGNIA/ 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 



XLVL 



Bradley Moore Davis. 



(with PLATES IX AND x) 



Although Saprolegnia is a form of considerable interest in 

 connection with the problem of the so-called multinucleate 



4 



gametes, nevertheless investigations have not been carried 

 forward upon it with that attention to cytological detail that 

 has recent'y been given to other Phycomycetes, e, g,, Albugo, 

 Peronospora, Pythium, and Sclerospora. 



The present paper deals chiefly with the events of oogenesis 

 and a comparison of this process with the development of 

 zoospores. The material employed was apogamous, indeed 

 apandrous, for specimens were chosen entirely free from anther- 

 idia to the end that the investigation migfht be relieved from 

 the dispute on the sexuality of these fungi. However, as will 

 be seen, the results have an important bearing on the well- 

 known binucleate eggs, assumed by Trow to be stages of fertili- 

 zation. At the end of the paper will be found an account, 

 entitled ** Theoretical Considerations,'' which deals with a number 

 of topics suggested by this study in relation to recent investi- 

 gations upon Phycomycetes and Ascomycetes. 



The material was isolated in pure cultures and cultivated for 

 several months on various substrata, during which time the 

 writer had the opportunity of observing and confirming many of 



^ Published also in Decennial Publications, the University of Chicago, L lO : 225- 



257. pis, /J, 16. 1903, 



233 



