88 Cattle Problems. 



by the solvent juices of the stomach and intestines, pass into 

 the blood current, where it constitutes the solid parts of 

 the crude or incompleted material of nutrition. As the 

 blood flows forward through the lungs, the ox)'gen obtained 

 by breathing combines with various necessary s,ubstances, 

 derived from the food and brought forward in the crude 

 blood, the combination being in the red corpuscles, which 

 contain the oxygen that completes the blood, by giving the 

 property that enables it to flow or circulate. The blood 

 will not circulate without the oxygen, that reddens it in 

 the lungs. Hence the oxygen obtained by breathing is 

 the agent that makes it circulate, and supplies a leading 

 nutritive quality. After being made capable of circulating 

 by a due proportion of oxygen, the blood flows forward 

 into the millions of tiny capillary vessels in all parts of the 

 muscles, and muscular organs, bones and skin ; to all parts 

 in which red blood is found. 



The blood conveys the pabulum and latent heat into the 

 muscles, skin, and other parts; and the heat is there reg- 

 ularly liberated and made active by the process of assimila- 

 tion, by which the worn-out material of the parts or organs 

 is detatched and passes away in the venous blood ; while the 

 fresh matter brought forward in the artery blood is appro- 

 priated in renewing the substance of the tis.^ues, in place of 

 the effete matters that pass away in the venous currents. 



The renewal of the tissues in all parts of the body, by 

 assimilation, is a reciprocating vital process, by which 

 about as much worn-out material is detatched as the quan- 

 tity of fresh material used for renewal by assimilation. It 

 is during this process of assimilation, in which oxygen is 

 the chief agent, that heat is set free, and by its motion be- 

 comes sensible, or felt as warmth in all parts of the body, 

 being most sensible in the skin, that organ being most ex- 

 posed to external impressions of heat or cold. Oxygen 

 brought forward in the arterial blood combines with carbon. 



