616 DIGESTION. 



facilitates its course. When it has reached the large intestine, it first 

 accumulates in the caecum, which being cellular or pouched like the 

 colon necessarily detains it for some time. In proportion, however, 

 as the caecum becomes filled, the peristaltic action is extended from 

 the small intestine, and the matter is sent into the colon, the cells 

 of which are successively filled ; first, those of the ascending, and 

 then those of the transverse and descending colon, as far as the annu- 

 lus or commencement of the rectum. The whole of its progress through 

 the large intestine is slowly accomplished. Independently of the 

 pouched arrangement, which retards it, a part of the colon ascends, so 

 that the faecal matter must often proceed contrary to gravity. It 

 becomes, moreover, more and more inspissated in its progress towards 

 the outlet ; and the peristaltic action recurs at greater intervals than 

 in the upper portions of the tube. The importance of such a reservoir 

 as the large intestine is obvious. Without it, we should be subjected 

 to the inconvenience of evacuating the faeces incessantly. 



Before the excrementitious matter reaches the lower portion of the 

 small intestine, it has not the fecal odour ; but acquires it after having 

 remained there for a short time. The brownish-yellow hue becomes 

 deeper; but its consistence, smell, and colour, vary considerably, 

 according to the character of the alimentary matter ; the mode and 

 degree in which chymification and chylification have been accomplished; 

 the habit of the individual, &c. &c. The faecal matter, as we find it, 

 consists of the excrementitious part of the food, as well as of the juices 

 of the upper part of the canal, that have been subjected to the digest- 

 ive process ; of the secretions, poured out from the lower part of the 

 intestine, and also, of substances, that have escaped the digestive 

 actions of the stomach and small intestine, and are often perceptible in 

 the evacuations. The peculiar faecal impregnation is probably depend- 

 ent upon a secretion from appropriate follicles those of Peyer, for 

 example ; and we can thus understand, if we take into consideration 

 the digestion of the different secretions, why faecal evacuations may 

 exist, when the individual has not eaten for some time, or taken but 

 little nourishment. 



Some physiologists have believed, that chylification takes place even 

 in the large intestines, and that chylous absorption is more or less 

 effected there. M. Viridet 1 asserted, that the caecum is a second sto- 

 mach, in which a last effort is made to separate from the food the 

 digestible and soluble portions it may still contain. In herbivorous 

 animals, according to him, an acid solvent is secreted in it. MM. 

 Tiedemann and Gmelin seem to admit the fact ; and likewise think, 

 that the fluid, secreted by the inner membrane of the intestine, assists 

 in the assimilation of the food by means of the albumen it contains, and 

 that faecal matter is formed there. From various experiments insti- 

 tuted by Professor Schultz, 2 of Berlin, he infers, that the food in the 

 caecum becomes not only a second time sour, but that the acid chyme 

 is there neutralized by the access of bile in the same way as in the duo- 



1 Tractatus Novus de Prima Coctione, &c., Genev., 169J.. 



2 Lond. Med. and Surg. Journ., Oct. 31, 1835 ; cited in Amer. Journal of the Medical Sci- 

 ences, Nov., 1836, p. 203. 



