374 C. M. Child 
of the circumference the mesenteries are more completely removed, 
at others less completely; sometimes certain mesenteries are only 
slightly extruded, others almost entirely, so that the part of any 
given mesentery which is removed will differ greatly and cannot 
be controlled. But the important point is that those regions 
where the removal of the mesenteries is most complete near the 
cut end are apparently the regions where the greatest degree of 
change in the body-wall and the most active growth after closure 
occur. In other words, the regions where the greatest change 
results from the operation are the regions which show greatest 
evidence of that change in their later behavior. 
Fic. 31 
My observations of these pieces lead me to believe that, in at 
least many cases, those regions of the circumference where the 
mesenteries were most completely removed are the regions where 
groups of tentacles are most likely to appear. It is difficult to 
attain certainty on this point; after closure regions of greater trans- 
parency and more active growth can often be distinguished at 
different points of the circumference along the line, of union and 
examination of these regions shows either no distinct continua- 
tions in them of the mesenteries which, farther away from the 
line of union are visible through the body-wall, or else very deli- 
cate, evidently newly formed mesenteries which may connect with 
the old mesenteries. 
It is to be expected that regions in which the original organiza- 
tion and correlation of parts have been more completely eliminated 
will present more favorable conditions for the establishment of a 
