138 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



granular masses are clearly visible in the region previously occupied 

 by the branch and in the interstices of the parenchyma. In the 

 course of two to three months this disintegration proceeds so far that 

 in the terminal regions of the body only an unbranched axial in- 

 testine remains intact. Meanwhile the disintegration of the lateral 

 branches is advancing from the terminal regions toward the middle 

 region of the body : the branches in the pharyngeal region are the 

 last to show traces of disintegration. This disintegration and dis- 

 appearance of intestinal branches appear to be essentially atrophy 

 as the result of disuse. In the absence of food the intestinal con- 

 tents diminish in quantity, and in the course of time become insuffi- 

 cient to fill the whole intestine, even to a moderate degree. Those 

 parts of the intestine which are least often expanded by contents, 

 or from which the contents are most frequently forced out by con- 

 traction of the body, viz., the terminal regions, are the first to 

 undergo atrophy. The atrophy gradually extends toward the middle 

 region, those parts near the pharynx being the last afifected. This 

 fact indicates that Bardeen is correct in his belief that the pharyngeal 

 region is a region of " greatest intestinal pressure." The axial in- 

 testine does not vmdergo atrophy, though it is often reduced in size, 

 especially its terminal portions. Even after several months it con- 

 tains a thick, dark, granular fluid, which is forced to and fro in it 

 by the contractions of the body. Probably the stimulation of the 

 intestinal walls by this fluid is sufficient to prevent disintegration of 

 this part of the intestine. 



A very interesting modification of this process of atrophy was ob- 

 served in numerous pieces from the posterior region of the body, 

 which were kept for four months or more. These pieces did not 

 regenerate a head or pharynx : they showed little power of move- 

 ment beyond peristaltic contractions, and there was no communica- 

 tion between the intestine and the exterior. In the course of about 

 three months all lateral branches of the intestine had completely dis- 

 appeared, leaving only a straight, unbranched axial intestine. 

 Within the axial intestine in every case was found a fluid or semi- 

 fluid residue, either of the intestinal contents, or of disintegrated por- 

 tions of the intestinal wall, or of both. This residue, dark in color 

 and filled with granules, is forced to and fro in the axial intestine by 

 the contractions and movements of the piece. During all this time 

 the piece is of course decreasing in size, but the dark residue in the 

 axial intestine apparently does not decrease in quantity after a cer- 

 tain time. Undoubtedly all nutritive substances have been removed 

 from the fluid long before this, and probably equilibrium as regards 



