PROTOCOCCUS PLUVIALIS. 521 



green gonidia, and consequently furnished with all the 

 requisites for existence, burst the mother-cell, and become 

 free. Should they belong to the second generation, and 

 consequently arise from the division of already motile 

 cells, the young individuals frequently remain in con- 

 nexion, and revolve together until at last they become 

 detached from each other. From this circumstance 

 arise aggregations of 4, 5, 6 minute globules; even 8 

 individuals occur together in a mucous envelope. Some 

 cells divide even into 12 or more, and revolve in com- 

 mon like a Volvooc. 



Other forms of division are noticed. Besides this 

 mode, multiplication by gemmation takes place, both in 

 the still and motile forms (innovatio). Within the 

 mucous envelope there is formed a parietal, colourless 

 vesicle, into which the red atoms pass from the mother- 

 cell, and thus gradually colour the young individual. 



The author proceeds to describe the effects of desicca- 

 tion, &c, 3 upon the appearance and colour of the varieties 

 of Htematococcus, and notices the extraordinary power 

 of vitality after desiccation for many months, when the 

 Hcematococcus has been slowly dried ; and even after 

 quick drying, it would seem that development is possible 

 by means of spores and gemmules from the form named 

 H. atomarius. Arid even in some cases after such indi- 

 viduals had been swallowed and evacuated by Infusoria, 

 for instance, by Philodina roseola. Even momentary 

 exposure to a boiling temperature does not destroy their 

 vitality altogether, though it does so partially. 



A summer temperature, however, very much pro- 

 motes the development of the Haniatococcw, so much 

 so, in fact, that occasionally all the stages are gone 

 through within eight days. Commonly, the motile forms 

 retain that condition only for a few days or hours. When 

 some in the motile form are placed in a glass of water, 

 within twenty-four hours a red border appears at the 

 margin of the water as it evaporates, consisting of still 

 vesicles undergoing division, whilst beneath it is a 



