20 DESMIDS OF THE UNITED STATES. 



germination. I have found many such cysts enclosing sometimes 

 only one large specimen, as Euastrum verrucosum. but more fre- 

 quently sis. or eight smaller Desmids in one cyst : these were at 

 first a source of perplexity. Upon consultation with men and 

 books I found Huxley to say: "Encystment is very common 

 among all the Oiliatn ; and a species of AmphUeptus has been seen 

 to swallow, or rather envelope a stalked bell-animalcule, and 

 then become encysted upon the stalk of its prey.'" 



Prof. Smith writes with reference to a case of encysted dia- 

 tomes : "the group of Xavicula seen, are simply a group that were 

 devoured and their protoplasm digested by an Amoeba. They 

 constantly are ejected in this way from the body of the Amoeba 

 after the nutriment has been abstracted, and look like an en- 

 cysted mass with an envelope complete." 



This subject of multiplication by regeneration is full of interest 

 for the microscopist, and opens a large and unexplored field. 



The frequent variations in outline of form in certain species is 

 calculated to mislead, and perhaps suggest notions of variation 

 of species, but close observation will soon dispel such notions, 

 and prove that they are nierely temporaj^ results of exhausted 

 vitality in the process of multiplication bj' division; they occur 

 most frequently in the latter part of the summer season. After 

 regeneration through copulation, the zygospores become winter 

 resting spores and lie dormant until the following spring, then 

 germinate and reproduce the true counterpart of the original 

 form of the species. 



