404 F. II. Krecker, 



sliould be ample for the body wall to regenerate if it were at all capable 

 of so doing. Tliere is therefore Httle basis for doubting that in tbese 

 Worms the presence of the intestine is a necessary factor in posterior 

 regeneration. 



The question arises, is the Stimulus exerted by the intestine merely 

 the mechanical one of contact or is it of another nature peculiar to the 

 intestine alone? The comparatively delicate character of the worms 

 made the introduction of foreign objects extremely difficult. Fortuna- 

 tely the mechanical Stimulus was supplied in some cases by ova which 

 came to lie between the end of the intestine and the posterior end of 

 the body wall. An ovum in his position filled the coelom completely 

 and pressed against the body v/all. Three such cases were observed 

 and in each the individuals lived at least a week (See series 5), and 

 yet the presence of an ovum in this position caused no regeneration. 



Although the body wall can not regenerate without the intestine, 

 still the latter can regenerate independently of the former. This fact 

 has been noted in the series of experiments already described and it is 

 still more evident in the following observations. 



On Jan. 16th 09, the intestine was drawn out of several worms 

 for from one to tv/o somites. Two days later one individual had begun 

 to regenerate a little tissue from the llth somite of the intestine. In 

 three days three individuals had formed al)out one-fifth of a segment 

 of intestine beginning at the I4th somite and in six days the intestine 

 of another had regenerated one-half segment. 



Feb. 16th 09. In this case the intestine was taken out of from 

 one to three somites. Ten days later in two individuals the intestine 

 had regenerated one segment beginning at the llth and the 12th so- 

 mites respectively. In thirteen days four had regenerated the intes- 

 tine for a length of two Segments beginning with the 14th or the loth 

 somites. In sixteen days two other individuals had re2:)laced three 

 Segments pf intestine beginning at the 12th somite. 



It is worthy of note that both in the regeneration of the entire 

 body and in that of the intestine alone comparatively little tissue is 

 replaced during the first week. In the case of the entire body usually 

 hardly more than the primordia of a few Segments are regenerated and 

 in the case of the intestine alone, but little tissue and sometimes none 

 appears. This is to be explained by the fact that during the first few 

 days after an Operation the organism is concerned in adjusting itself to 

 now oonditions ; the wound is being closed by a temporary plug which 

 is later rejilaced by a more thorougli healing and preparations are 



