Miscellaneous. 395 



foul water. A few ParanKecia placed in a drop of water swarming 

 with Bacterise, Vibrios, Bacilli, and other microbes will render it in 

 a few hours as pure and clear as spring water. The Stentors, 

 Euplotc^, and many Oxytrichidte are omnivorous, and live upon 

 Schizomycetes and small Infusoria drawn in by their vortices. 

 EncJielys, Didinium, Lcwriimaria, Leucophrys, the Trachelidoe, and 

 Goleps are carnivorous, although some of them can feed upon Schi- 

 zomycetes in the Zooglcea-state. 



In small aquaria with infusions the species of Ciliata appear 

 successively in a nearly constant order explicable by their peculiar 

 alimentary adaptation. At first the herbivorous species, finding an 

 abundance of Schizomycetes, swarm and clear the water of those 

 microphytes. Then come the Carnivora, which pursue and exter- 

 minate the herbivorous forms. 



Stylonijclua piistulata has been particularly studied by the author, 

 who followed day by day two separate cultures of it, during more 

 than three hundred successive generations, which lasted rather more 

 than eight months. Under the most favourable conditions of nutri- 

 tion this species divides once in twenty-four hours at a temperature 

 of 44°-.50° F., twice at 50°-59°, three times at 59°-68°, four times 

 at 68°-75°, and five times at 75°-80°. In the last case one indi- 

 vidual will produce thirty-two in twenty-four hours ; and thus at a 

 temperature of 77°-79° F. a single StylonycJna may produce a 

 million of descendants in four days, a billion in six days, and one 

 hundred billions in seven and a half days. The author estimates 

 that the body of a Stylonychia has a volume of 100,000 cubic micro- 

 millimetres ; hence it would take ten thousand to make 1 cubic 

 millim. and a million to 1 cubic centim. Protoplasm being about 

 equal in density to water, a million Stylonychice will weigh 1 gram, 

 a billion 1 kilogr., and one hundred billions 100 kilogr. Thus a 

 single Styhnycliia may produce 1 kilogramme of protoplasm in six 

 days and 100 kilogrammes in seven and a half daj-s. 



These numbers are obtained when the Stylonychice are abun- 

 dantly nourished with small Infusoria, but with vegetable food the 

 rapidity of multiplication and the size of the animals are consider- 

 ably reduced. 



Stylonychia mytihis has less power of multiplication than S. pus- 

 tulata. At a temperature of 42°-48° it divides only once in two 

 davs, at 50°-57° once a day, at 59°-64^ twice, and three times at 

 6G°-77°. 



Euplotes patella requires a temperature of 59°-68' to divide 

 once, and of 68°-75° to divide twice in twenty-four hours. Ony- 

 clwclromus grandis divides once in two days at 41°-44°, once a day 

 at 48°-53°, and twice at 55°-64°. Oxytriclia fallax twice at 57°- 

 61°, and three times at 62°-64°. Stentor cceruleus, of which the 

 fission was observed for a month, divides once a day at 75°-79° ; 

 and Spirostomum teres once in two days at 61°-64°. 



Paramcecium aurelia divides once in twenty-four hours at 57°-62°, 

 and twice at 64°-68° ; Paramcecium caudatimi once at 59°-63° ; 

 and Paramcecium hursaria once in two or three days at o5°-59°. 



