94 C. M. CHILD. 



that of the plant for the tissues of Ccriantlins are bathed internally 

 and externally by water and it is very difficult to see how or why 

 a cut on one side of the body at a distance of two to three cen- 

 timeters from the tentacles should cause loss of turgor in those 

 tentacles directly above it. There are no vessels or tubes of any 

 kind running longitudinally in the body-wall. If the shock or 

 irritation resulting from the cut is the cause of the loss of turgor 

 why should it be transmitted only in the oral direction ? 



Apparently Loeb still holds the view originally expressed re- 

 garding these phenomena for he has recently called attention to 

 these experiments and to his conclusions (Loeb, '03). As a 

 matter of fact, however, the regeneration of these supplementary 

 partial discs and tentacles and the reduction of the tentacles oral 

 to them constitute most striking evidence in favor of the view 

 that internal, i. e., enteric, water-pressure is an important regula- 

 tive factor in Ccriantlins. There is not the slightest ground in 

 support of the conclusion that the direct effect of a cut upon 

 intracellular turgor extends beyond the cells in the immediate 

 vicinity of the injury. 



In my own experiments both C. membranaceus and C. solitarins 

 were used, the latter species chiefly. Similar results were ob- 

 tained from both species, as in the case of other regulative phe- 

 nomena. Description of a few of my experiments and a brief 

 analysis of the results obtained will show very clearly that the 

 supplementary partial discs and tentacles regenerate in exactly 

 the same manner as typical localized structures, and that reduc- 

 tion of tentacles above the accessory discs is due, like other 

 cases of tentacle-reduction described, to decrease in internal 

 pressure. 



The experiments group themselves under several categories : 

 the results differ somewhat according as the operation is within 

 the cesophageal region or aboral to it ; moreover, the effects of 

 these operations both upon regeneration of tentacles and upon 

 their reduction must be considered. I shall discuss first the 

 regulation of lateral openings in the cesophageal region in rela- 

 tion to tentacle regeneration, and tentacle reduction, and then 

 the regulation of lateral openings in regions of the body aboral 

 to the oesophagus in relation to tentacle-regeneration and reduction. 



