73 MANUAL OF CATTLE-FEEDIKG. 



The fat seems to be carried exclusively by the lacteals, 

 and to pass through the mesenteric glands and thoracic 

 duct into the left subclavian vein, as already desciibed. 

 Other substances pass more or less completely into the 

 blood. It will be leznembered that the lacteals in the villi 

 are surrounded by a net of capillary blood-vessels through 

 which blood is continually passnig, and there appears to 

 be no reason why the easily diffusible substances of the 

 lymph should not pass into the blood, especially since the 

 latter, being continually renewed, would act like a large 

 volume of fluid. 



Probably, then, the products of the digestion of the 

 carbh}drates — viz, sugar, lactic acid, etc. — pass, in large 

 pait, into the blood and through the portal vein, the capil- 

 laries of the liver, and the hepatic vein, to the heart. The 

 same would be true of the amides formed by the action of 

 the pancreatic juice and by decay from the albuminoids, 

 and to a less degree of the peptones, while unaltered pro- 

 tein, if resorbed, would be largely retained in the contents 

 of the lacteals, owing to its slow rate of diffusion. 



All these statements are, however, to a certain extent, 

 speculative. It is highly probable that the resorbed mat- 

 ters undergo chemical change in the act of resorption by 

 the epithelial cells ; at any rate they undergo such rapid 

 alteration after resorption that only traces of most of them 

 can be observed either in the lymph or in the blood of the 

 portal vein. 



The Faeces. — By the process of resorption the chyle, 

 as it moves along through the intestines, is exhausted of 

 its soluble parts and takes on a more and more solid con- 

 sistency, and finally is voided from the body as the faeces. 



Tlie solid excrements consist of the indigestible part of 

 the food, those digestible parts which for any reason may 



