213 



Fig. 198. Mesothamnion caribaeum nov. 



spec. Development of cystocarps. a, the 



auxiliary cell is divided in three cells, b, 



more advanced stage. (A.bout 200:1). 



irregularly arranged walls in a number of small cells or rather short 

 filaments, the end cells of which are the antheridia (Figs. 196 d h). 



The procarp occurs 

 terminally upon short 

 branchlets (Fig. 195 6). 

 When fully developed it 

 (Fig. 197) consists of a 

 basal cell from which the 

 carpogonial branch issues, 

 and a sterile cell nearly 

 opposite to it ; in the 

 middle we find the large 

 auxiliary cell and above it 

 a sterile apical cell. The 

 carpogonial branch is com- 

 posed of 3 cells and the 

 carpogonium with the 

 trichogyne ; the last men- 

 tioned is rather robust, 

 nearly cylindrical and very persistent. By means of staining in 

 MAYER'S hsemalum I have been able to see the nucleus clearly 

 as well in the auxiliary cell as in the other ones of the procarp 



except in the carpogonium, this 

 most probably being due to the 

 bad preservation of the material, 

 this having been kept in rather 

 weak spirit. 



After the fertilization the auxili- 

 ary cell increases in size, and soon 

 two cells are cut off, one at both ends 

 of it (Fig. 198 a). These cells again 

 are divided into smaller ones (Fig. 

 198 b). 



Not having had sufficient mate- 

 rial I have not been able to follow 

 the development in detail, but the 

 result of the further growth is that 

 we get a large cystocarp composed 

 of several larger and smaller round- 

 ish bodies consisting of the nume- 

 rous carpospores (Figs. 199 and 200). Of these bodies the two 

 on each side are the largest; so far I have been able to follow 



Fig. 199. Mesothamnion cari- 

 baeum nov. spec. Young cysto- 

 carp, the trichogyne is yet pre- 

 sent. (About 120:1). 



