4o8 S. J. Hohiifs 



apparent as in the entire organism. 1 he piece kept going for- 

 ward and aborally a very short distance, then backward and orally, 

 circling about in nearly the same spot, with a regular, incessant, 

 rhythmical movement. In going forward the body became not 

 only elongated but curved toward the aboral side. When con- 

 traction occurred during its reversed movement, it was greater 

 on the oral than the aboral side as it is in the entire individual. 



The behavior of several other pieces taken from the two ends 

 of the body was essentially like those described. Sometimes the 

 pieces would swim about in a spiral course through the water for 

 several minutes, but eventually they all settled down to the same 

 regular back and forth movements. Pieces cut from the middle 

 of the body showed the same rhythmical movement, extending and 

 bending slightly aborally as they went forward, and contracting 

 more on the oral side as their motion was reversed. 



RHYTHMICAL ACTIVITY OF LOXOPHYLLUM 



When first observing the activities of Loxophyllum I came to the 

 conclusion that the frequent reversals in the direction of its move- 

 ments were due to reactions caused by minute objects with which 

 the sensitive anterior end ot the body came into contact. But 

 further observation showed that these reversals were due to inter- 

 nal rather than external causes. When specimens of Loxophyl- 

 lum were placed in water as free as possible from small particles 

 the same regularity of reaction was found to continue. When 

 gliding on the upper side of the surface film of a drop of clear 

 water Loxophyllum reverses its movement about as often as when 

 in the midst of objects with which it is continually colliding. But 

 any doubt concerning the inherent rhythmicality of its movements 

 is removed when we consider that the pieces into which the body 

 is cut move back and forth at about the same rate as the whole 

 animal. 



The cut anterior ends of the pieces of Loxophyllum are com- 

 paratively insensitive to mechanical stimuli, and there can be no 

 doubt that the movement of these pieces is a manifestation of 

 rhythmic activity comparable to the beating of the heart muscle 

 of higher animals. There seems to be no constant difference in 



