﻿342 BOTANICAL GAZETTE [may 



position are given great advantages over their neighbors and 

 are finally selected as the survivors. 



There are a number of instances known where sexual organs 

 sacrifice some of their nuclei to provide the remainder with the 

 cytoplasm at hand. Certain Fucales present notable examples, 

 and there will probably be found other illustrations among the 

 algae and fungi. Analogous conditions in animals have been 

 reported, as in oogenesis of Actinosphaeria (Hertwig, 1898), 

 and th*e well-known fate of supernumerary male nuclei in 

 polyspermy. In these cases there has not been reported the 

 same close relation between the surviving nuclei and metabolic 

 centers of the cell as between the favored nuclei and the coeno- 

 centra of the Saprolegniales and Peronosporales, In this same 

 connection we need more detailed accounts of oogenesis in the 

 Fucales, Vaucheria, and Sphaeroplea. 



The reasons why the oogonium overstocks itself with nuclei 

 are probably phylogenetic and recall the time when numerous 

 uninucleate gametes were formed from the protoplasm that now 

 acts as a unit (coenogamete). Such uninucleate gametes were 

 probably smaller than their homologues, the asexual zoospores, 

 as is so characterstic of algae. Among the algae it is generally 

 conceded that the small gamete swarm-spores result from 

 different conditions of nourishment than their asexual homo- 

 logues. It has been suggested that they are starved, but that 

 seems a clumsy conception of very intricate processes. But 

 there must be deep significance in the overproduction of sexual 

 nuclei during gametogenesis and its obvious association with the 

 deficient nutrition at the command of the gametangia. This 

 phase of the subject has not received the attention it deserves. 



SUMMARY OF THE INVESTIGATION OF SAPROLEGNIA. 



OOGENESIS. 



The material, Saprolegnia mixta^ was apogamous, being 

 entirely free from antheridial filaments- 



The resting nucleus has a loose linin network and a nucleolus, 

 and presents essentially the structure of the nucleus of higher 



plants. 



