NEW MYXOPHYCEAE FROM PORTO RICO 



17 



copious tognment, becoming decidedly laiiiellose and often vari- 

 ously colored, and with cells soon becoming- spherical after divi- 

 sion, as the extremes respectively of the genera Chroococcus 

 and Gloeocapsa, both together constituting a heterogeneous 

 group. The two genera may be kept as conveniences rather than 

 as distinct entities, and I have so considered them in placing the 

 various specimens of the collection. The placing of Chroococcus 

 limneticus Lemm. within that section of the group seems un- 

 warranted since that species as described has the cells embedded 

 within a coj)ious gelatinous tegument. 



My experience from examination of many collections and cul- 

 tures of both Chroococcus and Gloeocapsa reveals the fact that 

 they both have the same general method of multii)lication, viz., 

 at times certain single cells are liberated from a colony. These 

 usually become spherical and by division start new colonies. 

 However, never does the entire colony go into the one-celled 

 stage simultaneously, the cells in groups of two, four, or more, 

 enclosed within their special tegument, continuing to divide, be- 

 coming liberated from time to time by the dissolution of the 

 outer common tegument. 



The genus Anacystis of Meneghini, 1837,° has a very differ- 

 ent and distinct method of multiplication. Starting with a single 

 cell always, by repeated divisions, a colony, varying in size and 

 shape according to the species but usually spherical in form, is 

 evolved. At maturity, when the cells cease to divide, each cell 

 in the colony develops simultaneously a special, often highly 

 ornate, cell-wall, and the colonial tegument then dissolves and 

 liberates these resting cells. Kach again, after a period of rest, 

 starts another colony. The life cycle is very distinct and 

 definite. 



This cycle, although not definitely outlined by Meneghini, 

 was clearly indicated in his drawings {loc. clt.). I am here 

 emending the genus to that extent. Naegeli {loc. cit., pi. 1, fig. 

 F, 2-6) has included with the type of Gloeocapsa organisms 

 which, from the appearance of the drawings, have a life cycle 

 not that of the type which he designated, but that of Anacystis. 



5 Conspectus algologiae Euganeae, 6 ; Monographia nostochineai um Italicarum, 

 92, 1842. 



