Dr. F. Cohn oh a new (/enus of t/ie family of Volvocinese. 335 



tliem consists in the circumstance that in Chlamydomonas (and 

 Chlamydococcus) the individuals produced by the division of the 

 green globes separate after the absorption of the parent-envelope, 

 and live on as individuals, while in the other Volvocinea the 

 daughter-cells produced by the division of one green primordial- 

 cell remain connected by the persistent parent-cell as by a com- 

 mon envelope, and move about as a well-defined body composed 

 of many cells. 



While Chlamydococcus is a unicellular Alga in the strictest 

 sense of the word, never composed of more than one cell at any 

 period of its growth, and each division forms the commencement 

 of a new individual, the remainder of the Volvocinea present 

 themselves as families of cells, in which a definite number of 

 equivalent cells are combined in some measure into an individual 

 of a higher order. Consequently, Chlamydococcus bears the same 

 relation to the rest of the Volvocinece as Pleurococcus to Palmella, 

 Cyclotella to Meloseira, or as Vorticella to Epistylis, and Hydra 

 to Campanularia or Tubularia. On the other hand, Trachelomonas 

 and the analogous forms do not belong to the vegetable kingdom 

 at all, but are nearest allied to the Astasicea, and appear as loricated 

 EuglencB (not as loricated Monads, as Ehrenberg assumed). 



The researches of Alex. Braun, like my own, have proved 

 most distinctly that Chlamydococcus can only be placed with 

 propriety among the Algre. It is distinguished, indeed, from the 

 moving germ-cells by which far the greater part of the species 

 of Algae are propagated, both by a somewhat more complex 

 structure and by the circumstance that the motion lasts for a 

 very long time, and finally, by the power of the moving cells to 

 propagate as such, without entering into the state of rest (ger- 

 mination), otherwise than as quite a temporary condition. But 

 these objections touch only to some extent the specific character 

 of Chlamydococcus and the Volvocinece generally as unicellular 

 plants ; and they do not stand there among the Alga altogether 

 without intermediate conditions, as Alex. Braun has proved in 

 his 'Verjungung^ (/. c. 227)*, especially from the long move- 

 ment of the Volvocinea, 



On the other hand, the external form, like the chemical and 

 morphological organization of the contents, the laws of motion 

 and the general physiological phEenomena, especially however 

 the behaviour in the transition into the condition of rest, in 

 Chlamydococcus, agree so perfectly with the moving spores, the 

 transformation of which into undoubted plants has been demon- 

 strated with scientific clearness, that no unprejudiced observer 



* Thuret found the swarming-cdls of Ulothrix mucosa in motion after 

 tliree days (Ann. des Sc. Nat. 1850, 248). 



