90 



WILLIAM A. KEPNER AND ARNOLD RICH 



The observations of the men of the class in general zoology 

 suggested that perhaps a disturbance of thigmotactic conditions 

 resulting from shallow water or pressure of the cover-glass were 

 responsible for the autoamputation of the proboscis and that its 

 reaction was not due to disorganization of the body or parts 

 of the body. This suggestion is further supported by two ob- 

 servations made later bv ourselves. On two occasions w:e had 



D D 



Fig. 4 B, two-thirds of proboscis-sheath and posterior portion of body cut 

 away, proboscis active and ingesting body proper; C, proboscis active after auto- 

 amputation; D, sphincter of proboscis removed. 



drawn away the water from specimens, so that the worms had 

 but a mere film of water over them. In these specimens, thus 

 stranded in quiet shallow water, it was noticed that the proboscis 

 had broken from the body in each case and was swimming or 

 wriggling about within the sheath. To one specimen water was 

 added as soon as the proboscis had freed itself. After the ad- 

 dition of this water the proboscis left the sheath and swam 

 about in the water quite as actively as did the body proper 

 from which it had been separated. In the other specimen the 

 body proper, while in the shallow water, became so intimately 



