!74 BOTANICAL GAZETTE [march 



thorough study of the life-cycle of chromosomes; unfortunately not 

 much of such work has been done in algae. The work of Farmer, 

 Williams, and Strasburger dealt only slightly with the first two 

 mitoses in the oogonium, where it was inferred, but not actuall 

 observed, that the reduction of chromosomes takes place. Mitoses 



- 



in the antheridium, from the first division to the development of 

 mature sperms, were not studied. In the present investigation, 

 special attention is paid to the behavior of chromosomes in the first 

 and second mitoses in the oogonium, and to mitoses in the antheridium. 

 The results here presented are based upon a study of Fucus 

 vesiculosus L. Material was collected and fixed at Woods Hole, 



March 



A 



Flemmin 



proved to be most satisfactory. There 

 are several points of interest and importance in regard to the relation 



mitotic figures and environme 



antheridium 



thallus. In general, the plants collected one or two hours after being 

 covered by the tide were full of figures. Material was imbedded in 

 paraffin with a melting point a little less than 52 C. Sections were 

 cut 3 /*, sometimes 5 n thick. Flemming's saffranin and Heiden- 

 hain's iron alum hematoxylin, with or without counterstains, were 



were made. 



accompany 



John M. Coulter and Charles J 



I am indebted for their kind suggestions and criticism during the 

 progress of this work. 



MITOSES IN VEGETATIVE CELLS OF THE THALLUS 



Any young part of the thallus, when well fixed, showed figures 

 available for study, especially in the apical region, in the adventitious 

 outgrowths which are not infrequent, and in the early stages 



l. The nuclei in the thallus, e»** 

 in cases of young sporelings, are generally very small and dime 

 to study; but to make certain as to whether the number of chromo- 

 somes remains constant in the thallus grown under normal condition 



„ i.1 1 . , . ° . .^oorpsOf 



cryptosomat 



mitoses at vanuu= stages 



