MOVEMENTS, KTC, OF I'K'KSTT-WATKi; I'LANAinAXS. G33 



feeding begins is not inmicdiately apparent, but I am inelined 

 to think its purpose is to intimately test the substance with 

 regard to its availability as food. Some evidence on tliis 

 point and further discussion regnrding it will be introduced 

 later. 



After the preliminar}- pause nnd ^^ gripping" of the food 

 the worm glides up on to it to begin active feeding, l^he 

 position taken by the worm brings out a very nice correlation 

 in reflexes. In a ver}' large number of cases (certainly over 

 75 per cent., so far as my observations have gone) the worm 

 advances over the food until the pharyngeal opening is 

 exactly over the place where the first "gripping" occurred, 

 and there the pharynx is extruded iind feeding begins. 



Fic. 30. — Diagram showing great extension of the pharynx. Tlie 

 stippled area represents food substance on wliirh the phmarian 

 is rest in?. 



When the worm reaches this position the posterior i^art of 

 the body relaxes and takes on the appearance chai-acter- 

 istic of the resting specimen. The pharynx is thrust out, 

 and becomes attaclied very quick!}'. As it passes out through 

 the opening in the body-wall it becomes usuall}' considerai)ly 

 extended, and its diameter becomes correspondingly smaller 

 than when it is in the pharyngeal sac. It ma}' or may not 

 attach to the food directly beneath the body. When con- 

 ditions are favourable it usually does, and consequently 

 cannot be seen on looking down on the animal from above. 

 On the other hand, I have frequently seen it stretched out 

 and attached some little distance to one side of the body, as 

 shown in Fig, 30. The stinnilus, causing the extrusion of the 



