68 ROSALIND WULZEN. 



This result is contrary to that of Pearl, 1 and more extended 

 than that of Bardeen. 2 



A certain degree of independent activity on the part of the 

 pharynx is thus indicated. The same thing could be suspected 

 from the feeding reaction of normal worms. Often a normal 

 worm will come to rest side by side but not in contact with a 

 piece of meat. The pharynx will be extruded and directed 

 toward the meat and will stretch out to reach it to such a degree 

 that the portion of the body to which the pharynx is attached 

 will be pulled out of place, making an indentation on the dorsal 

 surface of the worm. The worm itself will not move at all to 

 help the pharynx, whereas if the pharynx were not extended the 

 chemotropic reaction of the whole worm would carry it directly 

 up to the meat. 



There seems to be a twofold chemotropic response, that mani- 

 fested by the movement of the whole worm toward the meat and 

 that manifested by the movement of the pharynx. Both re- 

 sponses are accurately directed, but when the one is active the 

 other is apparently inhibited. Thus when the stimulation is 

 comparatively weak, the sensitive cells of the skin respond in 

 such a manner that the worm moves directly toward the meat 

 and ordinarily the pharyngeal reflex is entirely in abeyance. 

 When, however, the stimulation is very strong, as upon direct 

 contact with meat or upon the first contact of a very hungry 

 worm with meat-juice, the pharyngeal reflex dominates for a 

 longer or shorter time. When the anterior end of the worm is 

 removed, with it are taken away those portions of the skin which 

 are most sensitive to chemical stimulus. Now a weak stimulus, 

 as that of diffusing juice, calls forth a more pronounced pharyn- 

 geal response as though some inhibition were removed. 



Some independent chemotropic response seemed so certainly 

 to be located in the pharynx that the question of the activity of 

 the isolated pharynx was raised. If a section is made through 

 the anterior extremity of the pharyngeal sac gentle pressure 

 will force out the pharynx which is now entirely separate from 

 the body. It must be observed that pharynxes so prepared 

 vary as much in sensitivity as do the worms from which they 



1 Pearl, R., Quarterly Journal of Microscopical Science, 1902-3, Vol. 46, p. 509. 



2 Bardeen, C. R., American Journal of Physiology (1901), Vol. 5, p. i. 



