NO. IQ.] ECHINODERMS OF CONNECTICUT. 



The following interesting observations by Clark,* show the 

 ability of the common Synapta to regenerate missing parts. 



" A number of experiments were made to test the tenacity of 

 life and the possibility of regeration in synaptas, and the results 

 show that inhcerens is not a very sensitive animal. If an individ- 

 ual is cut in two the anterior end will live and grow as well 

 apparently as any normal specimen, but the posterior end will 

 only live for a few hours, or perhaps a day. So far as I could 

 see, the only reason for its death was its inability to take in 

 food ; and I am inclined to think that if food could be provided 

 the posterior half would live as well as the anterior. It seemed 

 to make no difference whether the bisection occurred near to 

 the head or far from it ; the head always lived, and in the course 

 of two weeks would show perceptible signs of growth. All that 

 seemed to be necessary was the mouth and a small part of the 

 digestive tract. That it was not the tentacles which were essen- 

 tial was shown by the fact that synaptas lived all right without 

 them. Two or more tentacles were cut from a number of syn- 

 aptas in two cases every one being removed yet they all lived 

 and burrowed in the sand with more or less ease; and not only 

 did they live, but regeneration began at once, so that in two 

 weeks the new tentacles were large enough to bear a digit on 

 each side. At first I thought the nerve ring was the essential 

 part, but that seems to be doubtful, for the nerve ring was care- 

 fully and completely severed in a synapta without apparently 

 causing any inconvenience. In other specimens it was cut in two 

 or even three places, but with the same result. In no case were 

 any serious effects shown, and the animals lived and burrowed 

 in the sand with apparently as much ease as ever. I made no 

 microscopical examination to show whether the nerve ends re- 

 united or not, but the cuts apparently healed in a short time. 

 The most striking fact was that with the cutting of the nerve 

 ring there was not the least evidence of any lack of coordination 

 in the movements of the tentacles, nor of the muscles of the 

 body." 



Bull. U. S. Fish Commission, 1899. 



