Sensory reactions of Holothuria surinameusis. 



247 



that this process is a normal mode of reproduction in H. surina- 



mensis. 



Table I. 

 Size of the regenerated (?) terminal regions — H. surinamensis. 



Total length 



Length of 



Length of 



extended 



anterior regions 



posterior regions 



cms 



cms 



cms 



6,7 





1,2 



10,0 



1,4 





10,0 





1,0 



12 



1,0 







12,3 



io 



. 



14,6 





0,8 



17,0 



2,3 





17,5 



2,4 







18,0 



1,2 



— 



,^) Experimental. In connection with experiments on the 

 nervous system, operations were performed on Holothuria which in- 

 «identlj^ brought to light some interesting phenomena of regeneration. 

 Since the observations of Dalyell (1840, 1847) it has been known 

 that some holothurians are able to make good the removal of parts 

 -of the body, but Toeelle's (1909) work indicates that in the genus 

 Holothuria this power is limited. 



When the body wall of Holothuria was cut, there followed a 

 set of activities making for the closure of the wound and the re- 

 paration of the lost part. Precisely as in the case of coelenterates 

 and annelids (cf. Eand, 1909), a prominent feature in the early 

 steps of wound reparation is the inbending of the cut edges; while 

 there is some question as to the extent to which various factors, 

 such as muscle contraction, amoeboid activity of tissue cells, etc., 

 are concerned in this process, experiments on Holothuria demonstrated 

 that both muscular activity and the slow movement or multiplication 

 of superficial tissue cells is involved. In the first experiment thin 

 fragments of the outer body layer were removed, without cutting 

 into the body-cavity, and the manner in which the surface thus 

 exposed was covered over was watched. 



Exp. 94,2. 



July 29, 11,30 A.M. Thin pieces of the outer pigmented layer 

 removed from the mid- dorsal region of 5 animals. The fragments cut off 

 Zool. Jahrb. XXXV. Abt. f. aUg. Zool. u. Physiol. 17 



