536 RAYMOND PEAlil;. 



as quickly as any other food. I liavu several tiiues seeu 

 specimens thus eaten. It is, in fact, possible, with a little 

 patience, to make a specimen eat a small piece cut olf the 

 posterior end of its own body ! This eating of each other 

 does not occur, so far as I have observed, unless an individual 

 is bruised so that some of the tissue underlying the epidermis 

 is exposed. Under these conditions juices escape from the 

 body and act ;is stimuli on the other worms. Under normal 

 conditions contact of one individual with another does not 

 start the feeding reaction, Avhich is a purely reflex pheno- 

 menon, cispablo of being started only by a certain set of 

 stimuli. Promiscuous cannibalism, such as Child (:Ul) 

 suspects to occur among individuals of Stichostem ma, I 

 have seen no evidence for among the Turbellaria.^ 



In the feeding the worm lies fully 'distended, with the 

 posterioi' two thirds of the body on the meat, or whatever 

 else is being used for food ; the pharynx is extruded, 

 frequently to nearly half the length of the body, audits end is 

 attached to the meat. During the feeding the very anterior 

 end of the worm is attached to the bottom of the dish, provided 

 the piece of food is not so large as to make this impossible. 



Besides the animal food which the worms will take so 

 readily, they also normally, probably to some extent, feed on 

 vegetable mattei', although I have not been able to induce 

 the typical food reactions (to be discussed later) with vege- 

 table material. The evidence for the statement that 

 vegetable food is used by planarians is of two sorts : (o) 

 specimens a,re frequently found extended on the stalks of 

 water plants, with the pharynx extruded and attached to the 

 stalks; and [b) the faeces which have been observed immedi- 

 ately after defecation have been found to consist largely of 

 finely divided plant tissue. It would appear, however, that 



' Biirdccu (: 01, A, p. 176) says, "Stroiii,^ planaiiaiis oficu \n-c.y upon weak 

 ones. Ill such instances the strong individual al laches its pharynx somewliere 

 upon the boi]y of tlie weak one, usually near tiic liead." I iiavc never seen 

 even the largest specimens eat smaller ones unless these latter were bruised 

 in some way. 



