HOW THE ANIMAL LIVES 239 



red blood globules, while the dark red hue is caused by the 

 comparative absence of oxygen. The liquid elements of the 

 blood (serum) can absorb and convey but little oxygen. In 

 order to have free and healthy breathing, therefore, the blood 

 must contain abundance of red globules, and these must be 

 well developed, containing a large amount of the red coloring 

 matter. Ill health, lack of sunshine, and various diseases, 

 which cause diminution of the red globules or of their coloring 

 matter, interfere with respiration and consequently with the 

 healthy nutrition and function of the tissues of the animal. 



426a. Persons who desire a detailed account of the physiology 

 of domestic animals, may consult F. Smith's "Manual of Veteri- 

 nary Physiology." Advice as to the treatment of animals is 

 contained in Law : s " Farmer's Veterinary Adviser."' 



