544 JOHNSON. [Vol. VIII. 



death ensues. Almost immediately after death disintegration 

 sets in. 



It would be hardly possible for any Infusorian to have a more 

 extensive bill-of-fare than the ]51ue Stentor. It devours not 

 only Protozoa and Protophytes of almost every group, but small 

 Rotifers as well. The latter, together with Paramecium, 

 Stentor ignetis, and dwarfs of its own species, are among the 

 larger prey captured by this voracious animalcule. The booty 

 sometimes equals nearly one-third the bulk of its captor. I 

 have never observed the deglutition of these huge morsels ; 

 they must dilate the very distensible oral spiral to the utmost. 

 The cannibalistic habit of 5. cceniletis is not without interest. 

 It shows how large and vigorous members of a colony may 

 survive a period of scarcity, and at the same time reduce the 

 number (always large at such times) of the dwarfs in the 

 community. 



D. Defecation; Position of Anus. 



One of the favorite doctrines of micrographers is that of a 

 localized place of defecation in the Infusoria. It is not 

 commonly pretended that this so-called "anus" is a permanent 

 structure, or visible at any time except at the evacuation of 

 foecal matter. An anus, then, among Infusoria is held to be 

 not structurally but physiologically present. 



But are we certain that there is a fixed place of defecation } 

 Observations on this point are rather difficult to obtain, and 

 often require long and patient watching. Consequently, the 

 number of observations for any one form are generally very 

 few; and, to make the matter still more doubtful, observers are 

 by no means unanimous in their statements regarding the 

 position of the anus in one and the same species. This is 

 commonly held to be due to careless or incorrect observation. 

 May it not rather be due to variation in the place of defecation .? 



My study of the defecatory process in the Stentors has led 

 me to think that the temporary anus of the Infusoria is not so 

 fixed in position as is commonly held. I have many times 

 observed the evacuation of faecal matter by ^. c(unileus and 

 5. roeselii, and have, as a rule, found that it took place in the 



