No. 4-] CORDYLOPHORA LACUSTRIS. 207 



While no chemical analysis was made of the quantitive com- 

 position of the water at the beginning and conclusion of the 

 observations, it is, however, evident that it must have been 

 almost completely changed in the several operations through 

 which it passed. 



Lankester 1 has recorded the fact that Corclylophora may be 

 kept for some time in cans of water if kept in a dark place. 

 My observations show that this precaution is not essential, 

 since they were frequently exposed to direct sunlight and 

 were constantly open to strongly diffused light in a north 

 window. The following extract from a letter of Mr. Britcher 

 will show that his own observations on this point are quite 

 in accord with my own : " From December i 5 to January i 5 

 they were kept in the cellar, and when taken out only a few 

 individuals seemed to be living. Since this time they have 

 been on my window, where they get direct sunlight from 2 to 

 4 P.M. The water has frozen several times, once apparently 

 solid. . . . To-day, March 5, there are at the lowest estimate 

 over a hundred individuals in the colony." 



At the present writing, October 20, both hydroids and 

 barnacles are still living in less than a pint of water contain- 

 ing only a trace of salts in solution, the hydroids feeding 

 freely upon the Ostracoda, entangling them in the long and 

 graceful folds of their tentacles and engulfing them entire. 

 They seem also to be reproducing both by budding and from 

 sexual gonophores in perfectly normal fashion. While the 

 barnacles are alive and sweeping their tentacles as usual, the 

 movement is apparently feeble and would indicate a low stage 

 of vitality. 2 



1 Qiiar. Journ. Mic. Sci , vol. xvi, p. 26. 



2 Since the foregoing " Notes " were in type the vessel in which the organisms 

 described were originally placed has been reexamined with some care and not a 

 little interest. Although left without attention of any sort during the entire year, 

 except for the precaution of a close cover to prevent access of dust or loss from 

 evaporation, colonies of hydroids are still living and thriving apparently as normal 

 as when first examined. It should be said, however, that those living at present 

 are not the identical colonies, though of course direct offspring of them. No 

 food of any sort has been provided from without, though the examination revealed 

 the presence of several species of Protozoa, Rotifera, Vermes, and also several 

 species of Algae, Diatoms, etc. 



