252 MANUAL OF AGPJCULTUEE. 



taken into the body with the food and carried through it, without 

 having been assimilated. Unless there is consumption of food 

 rich in albuminous matter, or the latter is present in the former 

 in an indigestible state, the faeces contain but a small proportion 

 of nitrogen. The principal constituents are unassimilated inor- 

 ganic salts. 



To epitomise, alimentary substances are introduced into the 

 stomach, there to be broken up and dissolved, and passed thence 

 into the intestines, where tbey are still more completely fitted for 

 assimilation by the action of the absorbents. The saliva changes 

 insoluble starchy matters into soluble saccharine compounds, 

 until this process is arrested by the gastric fluid ; but the fluids 

 from the liver and pancreas renew the arrested operation when 

 such matters have been passed into the intestines. The albu- 

 minous compounds are in considerable part dissolved by the 

 gastric fluids ; those passing from the stomach undissolved are 

 further acted upon by the intestinal fluids. The oleaginous com- 

 pounds are broken up, but are otherwise unacted upon by the 

 gastric fluids. When subjected to the action of the bile and 

 pancreatic fluid, they are broken up into minute globules covered 

 by albuminous matter. The more solid and fibrous parts of the 

 food but little altered by these agencies are passed on to the 

 rectum, and thence defecated together with the remaining unab- 

 sorbed materials. The blood-vessels ramifying through the inner 

 coats of the stomach at once be^in to absorb all soluble com- 

 pounds — saccharine, albuminous, and inorganic — which can 

 penetrate the enclosing membranes of the vessels. These 

 absorbed compounds are passed together with the venous blood 

 through the several elaborating and secreting organs, there to be 

 prepared for assimilation in the tissues. The compounds result- 

 ing from muscular action and the breaking up of tissue substance 

 are in part absorbed by the lymphatics, but j^rincipally by the 

 blood-vessels. The compounds absorbed by the lymphatics are 

 supposed to be such as are not entirely excrementitious, but 

 still further capable of organisation and assimilation. The blood 

 is purified from all used up or unnecessary compounds during 

 their passage through the various excretory organs. 



Albuminous compounds pass by the several names of flesh 

 formers, or of proteine, plastic, and azotised, ix., compounds con- 

 taining nitro gen. Before absorption they are converted into a 

 compound named albuminose, which in the blood soon assumes the 

 forms of albumen and fibrin; the blood then circulating in the caj^il- 

 laries effuses through their enclosing cellular membranes into the 

 tissues its fluid and gaseous contents ; whereupon the albumin- 

 ous compounds go to build up and replace such bodies as the 

 fibrin and albumen contained in the muscular fibre of flesh, the 

 casein in milk, the gelatin in the bones, ligaments, horns, hoofs. 



