EXPERIMENTS IN THE KEEPING OF PLANKTON ANIMALS. 575 



occasions in the presence of these cultures for a considerable period, in 

 one case through 4 successive growths of Bacteria, extending over 

 some G weeks, the maximum life recorded — strangely, in this last- 

 mentioned experiment — being 48 days. Some notes concerning a few of 

 these experiments are appended : — 



l-litre Flasks. 



(No. 141.) In sterilised " outside " water, impregnated once with 

 peptone, on the 1st day, and cleared of Bacteria on the 9th day by 

 Euplotes. 



Of about 6 Calanoids which were introduced on the 13th day, 3 

 {Acartia) were alive and active 34 days later. The maximum life period 

 was not recorded. 



(No. 140.) In sterilised " outside " water, similarly impregnated once 

 with peptone, and cleared of Bacteria on the 8th day by a mixed culture 

 of Infusoria. 



Of about 12 Calanoids introduced on the 14th day, about 6 were alive 

 after 7 days, 2 after 10 days, 1 after 20 days. The last was not alive on 

 the 31st day. 



(No. 122.) In unsterilised " outside " water, impregnated twice with 

 peptone, on the 1st and 21st days, and cleared by contained Infusoria 

 on the 5th and sometime prior to the 30th day, respectively. 



Of the Calanoids contained in the water at the outset, 2 or 3 adult 

 Temora w^ere alive on the 30th day, and 1 on the 33rd day. 



The water was aerated for a time on the 21st and 23rd days. 



(No. 121.) In unsterilised " outside " water, impregnated four times 

 with peptone, on the 1st, 28th, 33rd, and 38th days, severally, and 

 cleared by contained Infusoria about 5 days later in each case. 



Of several small forms in the contained zooplankton, 1 Balaniis 

 nauplius was recorded alive as late as the 21st day ; a few Calanoids 

 were alive on the 28th day ; and 2 Calanoids were alive on the 48th day. 

 The water was decanted off into a clean flask on the 8th day. 



11-litre Bell-jars. 



(No. 145.) In unsterilised " outside " water, impregnated with 

 peptone on the 1st day only, and cleared by the contained Infusoria on 

 the 7th day. 



20 or 30 small Calanoids were alive on the 10th day, about 4 on the 

 29th day. None were observed on the 42nd day. 



(No. 144.) In unsterilised " outside '"' water, impregnated with 



