490 



C. M. Child 



and terminal cut edges of considerable extent existed after each 

 operation. Each time the wound healed the new tissue extended 

 a little further along the cut edges of the mesenteries, so that sepa- 

 ration of the regions oral and aboral to the wound was gradually 

 taking place. In Fig. 22, on the other hand the cut was not deep 

 and affected chiefly the body-wall, the mesenteries being but little 

 involved. Here the growth which follows each operation brings 

 about a bulging of the body-wall instead of a depression, as in 





the preceding case. In these two cases the reaction is exactly 

 the same, so far as can be determined, and the difference in the 

 result is due simply to the different physical conditions undei 

 which the reaction occurs. 



In cases like Fig. 22 more or less regulation of the shape usualK' 

 occurs if the animal is finally left undisturbed, but a shape like 

 that in Fig. 21 is, at least relatively, permanent, though regulation 

 may perhaps occur very slowly. 



