No. 3-] BIOLOGY OF THE STENTORS. 535 



of the body ; or if there is but one, it extends into both 

 (Fig. 61 A). 



IV. Biology and Physiology. 



I have set apart this portion of the present paper for an 

 account of certain experimental work and physiological obser- 

 vations. Many of the results are obviously far from complete ; 

 but are, I believe, not without interest, and will at least serve 

 to show how well-adapted are the Stentors for various lines of 

 biological and physiological experimentation. 



A. Rate of Multiplication. 



Most species of Stentor do not multiplv readily in con- 

 finement. This is especially true of the chlorophyll-bearing 

 forms, none of which have I seen in fission more than a very 

 few times. But, considering the enormous colonies these 

 species form in favorable localities, multiplication must be 

 more rapid under natural conditions. The most prolific 

 species that have come under my observation are 5. ccErulens 

 and 5. jveselii. If food be abundant, a few individuals of 

 vS. ccerideus will in a week or so become the progenitors of 

 thousands and fairly overstock the aquarium. 



After reading Maupas' account of his highly-successful 

 experiments upon the multiplication of Infusoria ('88) I deter- 

 mined to test the results he obtained from the propagation of 

 the Blue Stentor (p. 229). I followed his method closely, 

 using the excellent moist chamber that he recommends (p. 179), 

 and making the same sort of slide-cultures. For these I used 

 cover-glasses 18 mm. square, and elevated about a millimeter 

 from the slide with wax feet. For food I raised immense 

 numbers of Glaucoma scintillans in hay-infusion. These were 

 fed to the Stentors at intervals of a day or two, and were 

 devoured by them with the greatest avidity. The body of each 

 Stentor soon became gorged with the Glaucomas. Under 

 such generous feeding multiplication was rapid for a few days, 

 often one bipartition to every 24 hours, at a temperature 

 varying from 12° to 22° C. But that this rapid increase was 



