MOVEMENTS OF THE INTESTINES. 



275 



matter, or of the secretions and excretions mingled with it in 

 the stomach and intestines. 



3. It is probable that a certain mutual interchange occurs 

 between the gases contained in the alimentary canal, and those 

 present in the blood of the gastric and intestinal bloodvessels ; 

 but the conditions of the exchange are not known, and it is 

 very doubtful whether anything like a true and definite secre- 

 tion of gas from the blood into the intestines or stomach ever 

 takes place. There can be no doubt, however, that the intes- 

 tines may be the proper excretory organs for many odorous 

 and other substances, either absorbed from the air taken into 

 the lungs in inspiration, or absorbed in the upper part of the 

 alimentary canal, again to be excreted at a portion of the same 

 tract lower down in either case assuming rapidly a gaseous 

 form after their excretion, and in this way, perhaps, obtaining 

 a more ready egress from the body. 



It is probable that, under ordinary circumstances, the gases 

 of the stomach and intestines are derived chiefly from the 

 second of the sources which have been enumerated. 



Tabular Analysis of Gases contained in the Alimentary Canal. 



The above tabular analysis of the gases contained in the 

 alimentary canal has been quoted from the analyses of Jurine, 

 Magendie, Marchand, and Chevreul, by Dr. Brinton, from 

 whose work the above enumeration of the sources of the gas 

 has been also taken. 



Movements of the Intestines. 



It remains only to consider the manner in which the food 

 and the several secretions mingled with it are moved through 

 the intestinal canal, so as to be slowly subjected to the in- 

 fluence of fresh portions of intestinal secretion, and as slowly 



