﻿1903] 



BRIEFER ARTICLES 



137 



ec- 



T900, an archegonium was found which contained two well-devel- 

 oped ^gg cells of perfectly normal appearance. The supernu- 

 merary one lay directly over the other, being inserted as a link in 

 the axial row of cells present. Fig, 2 represents their arrangement. 



Each egg has cut off its ventral canal cell above 

 and is apparently ready for fertilization. One 

 neck canal cell {fic) is shown. It seems probable 

 that the upper tgg cell has been derived from 

 the lower neck canal cell by an abnormal 

 modification of the latter. This is the only 

 case, as far as I know, where two eggs have 

 been observed in the archegonium of any of 



the archegoniates. 



The nucleus of the spore cavity in pro- 

 THALLiA OF Marsilia. — The nucleus left with 

 the food material in the cavity of the mega- 

 spore on the formation of the prothallium 



Fig. 2.— Part of ven- 

 ter of archegonium of 

 Mnium,with two eggs and 

 two ventral canal cells; 

 ^^* egg cell; «r, neck 

 canal cell ; vc^ ventral 

 canal cell. X 1050. 



seems to have been much 

 neglected. Campbell 



{Mosses and Ferns, p. 404) 



figures this nucleus appa- 

 rently disorganizing in 

 Marsilia vesfi/a , a,nd 

 speaking of Azolla says 

 {i^id., p. 384) '' the nucleus 

 of the lower cell remains 

 in the upper part, and is 

 much like that of the pro- 



thallial cell." With these YiG.'s.—Marst'/ia Driimmondii, showing upper 



exceptions this nucleus part of megaspore with archegonium: vc, ventral 



seems to have received canal cell; e, egg; sn, large nucleus in megaspore 



little attention. While cavity ; .^, starch grains. X 670. 



Studying the prothallium of Marsilia Driimmondii, nott^ were made on 



