150 -; BOTANICAL GAZETTE [march 



the following solution: i per cent, chromic acid 25^=% i per cent, 

 glacial acetic acid is'^'^, i per cent, osmic acid lo-^^, water 50 ^<=. The 

 methods used after the material was thoroughly washed were similar 

 to those given in the pre\'ious paper on sporogenesis (loi). 



Description 



ATGETATIVE MITOSIS IN PROTHALLIA 



Immediately after the germination of the spore, the nucleus in the 

 prothallial cell is quite large, but shows a tendency to diminish gradu- 

 ally during the further development of the prothallia into many-celled 

 stages. The events of the mitosis in any vegetative cell of a prothal- 



those 



type 



^ X ^ — J 



For this reason no detailed account will be 



mention 



The chromatm reticulum of the resting nucleus of the prothallia, 

 ich has a ragged structure like that in a \'egetative cell of the sporo- 

 yte, becomes transformed into a spirem that runs an irregular course 



:hin the nucleus. manV tanorTpr! r.nrt= r^r Inr^r^c r-z^mino- I'nto r1o«;P 



membrane. The spirem then be 



and uniform in thickness and 



tinuous spirem {iig. i). A kino 



ery 



pole of the nucleus, consisting of a few fibers 



appears 



the lateral edges of the cone. With 

 membrane at the two poles, the fibers 



(k 



gmented from the 



points at which segmentation 



pirem 



may occur Have a certain regularity in relation to location within the 

 nucleus, -\lthough it is impossible to give an accurate explanation 

 of the mechanism at present, the fact that many free ends of the 

 chromosomes, immediately after segmentation, are directed toward 

 the poles may prove that the segmentation took place in bent points 

 of loops. Longitudinal splitting of the chromosomes appeared after 

 the completion of this segmentation. 



Contemporary' with the entire dissolution of the nuclear membrane, 

 the chromosomes show a tendency to arrange themselves paraUel to 



aas passing between the two poles (fig, 3) . The 



O 



