ANATOMY. 61 



THE CIRCULATORY SYSTEM. 



The average sheep has about one gallon of 

 blood; lambs scarcely a pint. This makes it an 

 easy prey to blood sucking parasites. 



The pericardium is usually buried in a mass of 

 fat. 



The heart is relatively large and situated prin- 

 cipally upon the left of the median plane, being 

 opposite the third to the fifth ribs. 



The arterial and venous systems are similar to 

 those of other animals. 



The lymph system is very well marked in the 

 sheep. 



THE NERVOUS SYSTEM. 



The diseases of the nervous system are many 

 and varied in the sheep, but as practically all 

 pathological lesions are caused by parasites, not 

 much can be done, except to perform a very care- 

 ful autopsy. 



The spinal cord is long and small, and the brain 

 is relatively small. The nervous system is similar 

 to that of other animals; perhaps not so highly 

 developed as in the horse and dog. 



THE ORGANS OF THE SPECIAL SENSES, 



The eye is round, and the lids rather thick. 

 The vitreous body is not very fluid. 



The ear inclines outward and upward, differing 

 in the several breeds. The auditory canal is small. 



The skin is thin and of a pinkish hue when the 

 animal is in good health, and covered with wool. 

 The caliber of the wool fiber varies from one five- 



