MAKXJAL OF CA'PTLE-FEEBTK-G. 75 



same in all. Those of most mammals are smaller than 

 those of man. 



The corpuscles contain, as characteristic ingredients, two 

 coloring-matters, known as hmnoglohm and oxyhemioglO' 

 liny of each of which there appear to be several varieties 

 in the blood of different animals. 



Arterial blood contains only oxyhsemoglobin. This sub- 

 stance is a bright red, crystalline body, having pretty 

 nearly the percentage composition of protein, but contain- 

 ing about 0.45 per cent, of iron. Its most remarkable 

 property, however, is the readiness with which it parts with 

 a portion of its oxygen and is converted into haemoglobin. 



In the body this process takes place in the capillary 

 blood-vessels, so that the blood as it returns from these 

 to the heart (the venous blood) contains both oxy haemo- 

 globin and haemoglobin. The latter is capable of the 

 reverse change, and in the lun^ takes up oxygen and is 

 converted back into oxyhsemoglobin. 



Besides these two coloring-matters, the corpuscles con- 

 tain an albuminoid which is precipitated by concentrated 

 salt solution, small quantities of two bodies known as eko- 

 le^terin and lecithin, some other organic matters, and the 

 usual ash ingredients, potash and phosphoric acid being 

 especially abundant. 



In addition to the red corpuscles the blood contains 

 colorless corpuscles, diffeiing in shape and appearance 

 from the red and generally larger. They appear to ^be 

 formed in the lymph before it joins the blood, but their 

 exact fimction is not well ascertained. Their number is 

 vastly less than that of the red, there being about one or 

 two of the former to a thousand of the latter. 



The plasma is a nearly transparent fluid, containing in 

 solution a large part of the nutritive matters of the blood. 



