THE ACTIVITIES OF CORYMORPHA . 323 



no essential part in geotropism. The motionless one was found 

 to have the ectoderm layer much torn. 



I next attempted the converse of the preceding experiment 

 and tried to destroy the neuromuscular mechanism and leave 

 the axial cells unharmed. Stalks that were known to possess 

 well marked negative geotropism were treated for ten seconds 

 with two per cent acetic acid to kill the ectoderm and were then 

 placed horizontally in an aquarium. In the course of five 

 hours no geotropic response had appeared in these stalks and 

 the experiment was concluded by a microscopical examination 

 of them. From each stalk a skin could be pealed off leaving an 

 axis of vacuolated cells whose consistency was that of a fairly 

 stiff jelly. In histological appearance these cells seemed to 

 be entirely normal and precisely like those that might be taken 

 from a freshly dissected living polyp. "I, therefore, believe 

 that the absence of geotropic reactions in these animals is not 

 due to any defect in the axial cells but is the result of the loss of 

 the neuromuscular coat. 



. Another way of testing this matter was by the use of anes- 

 thetics such as chloretone. Stalks of Corymorpha were placed 

 in a vertical position in sea-water containing chloretone till 

 their neuromuscular responses ceased whereupon they were 

 turned sidewise so that their chief axes were horizontal. All 

 remained in this position for five hours after which they were 

 put in pure sea-water. Within an hour after this change had 

 been made they began to show geotropic movements. Here 

 too the evidence favors the view that the negative geotropism 

 of Corymorpha is dependent upon neuromuscular activity. 



Although I do not believe that the axial cells of Corymorpha 

 take any active share in the geotropic responses of this ani- 

 mal, I am convinced that they play a considerable, though 

 passive, part in this response. If the headless stalk of a Cory- 

 morpha is inserted into a horizontal glass tube so that only 

 the distal half of it projects from the end of the tube into the 

 surrounding water, the stalk will bend upward where it is free 

 and assume in a short time a form not unlike a letter L. If 

 after having been two hours in this position, it is released, it 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 24, NO. 2. 



