VALVULCE CONNIVENTES. 209 



blood, in whatever way that is effected. It may be regarded 

 as a state of the general system in which the nerves of the 

 fauces and mouth are more sensitive to the condition of the 

 blood than the sensitive nerves elsewhere. 



Under the duodenal digestion in the horse a full account was 

 given of the ulterior processes to which the aliment is subjected 

 previously to its incorporation with the blood (see p. 68). 

 Nothing, then, seems to remain untouched on in this respect, 

 unless that the peculiar glandular structure of the mucous 

 membrane of the intestines has been rather cursorily treated of. 



Additional particulars as to Mucous Membrane of Ali- 

 mentary Canal The first point which attracts attention in 

 the intestinal mucous membrane is what relates to the valvulce 

 conniventes. These, indeed, are by no means universal in the 

 animals of the farm ; nevertheless, their character in a 

 treatise on animal nutrition requires to be made known. 

 These so-called valves, as seen in the human intestines, are 

 transverse folds of the lining mucous membrane in the 

 higher parts of the small intestine, by the presence of which 

 the extent of surface in that membrane is very much aug- 

 mented. The valvulce conniventes are found from the point 

 of the duodenum at which the bile-duct enters to near the 

 middle of the ilium that is, in the human body, through an 

 extent of nearly twenty feet of the small intestine. These 

 folds are large in the duodenum and placed closely together, 

 and this character they retain throughout the jejunum, while 

 in the ilium they gradually diminish in size and in proximity 

 until they finally disappear. No similar folds exist in any 

 part of the great intestines. The valvulce conniventes are 

 always much less distinct in other mammals than in the 

 human intestines. They belong to herbivorous animals rather 

 than to the carnivorous yet even in many of the herbivorous 

 they are hardly perceptible. 







