86 . WILLIAM A. KEPNER AND ARNOLD RICH 



REACTIONS OF FREED PROBOSCIS 



Our attention was first directed to the conduct of the pro- 

 boscis of this planarian while a class in general zoology was 

 studying the worm. It was observed, in many cases, by the 

 members of one section of this class, that, while they were study- 

 ing the specimens under supported cover-glasses, the animals 

 had cast off their proboscides which were swimming about, 

 oral ends first, by means of their external cilia and ingesting 

 various solid objects. In one instance Mr. Geiger called the 

 attention to the fact that the freed proboscis of his specimen 

 had turned upon its own body and had 'eaten a hole right 

 through it.' 



This observation suggested those made by Leidy ('47) on a 

 planarian which had more than one proboscis. He said, 



If one of these animals be punctured or cut, one or more of the 

 proboscides will be immediately protruded as if they existed under 

 pressure, and will move about in all directions, appearing as if entirely 

 without the control of the animal; or if one of the animals be crushed 

 between two slips of glass so that the proboscides will be torn from 

 their attachment, they move about involuntarily, always in a line 

 forwards or towards the mouth, which they do by contracting the 

 stomachal extremity towards the oral, the latter remaining fixed. In 

 this progressive course they constantly contract and dilate; the mouth 

 opens and any matter in the vicinity rushes in, when it is closed and the 

 matter passes onwards, and by the alternate contraction and dilata- 

 tion of different parts of the same tube, it is thrown backwards and for- 

 wards several times, and finally violently expelled at the torn extremity. 

 .... In fact, these curious independent movements caused me 

 at first to mistake the organs for viviparous young. ^ 



Darwin (43) also recorded that the proboscis of a land pla- 

 narian of Brazil lives long after the body has been destroyed by 

 salt. 



Bardeen ('01 a) described briefly the normal food reactions of Pla- 

 naria, and shows that a decapitated specimen will not find food ma- 

 terial in a dish, although such a specimen could "be made to eat if it 

 were placed on its back on a slide in a small drop of water. Under 

 the conditions mentioned, the pharynx is usually protruded, and will 



- Mr. W. H. Taliafero called our attention to this reference and that which 

 we have made from Walter ('08). 



