2U 



THE NATURE AND TREATMENT OF 



THE HEART, ITS FUNCTION AND DISEASES. 



VIEW OF THE INTERIOR OF A BULLOCK'S HEART. For explaiuition see p. 392. 



The heart is a wonderful and powerful piece of muscular mech- 

 anism ; its function is of the involuntary order, so that regular 

 contractions and expansions, or beatings, occur in the normal 

 state, without the knowledge and consent of the animal ; these 

 contractions and expansions, however, can be modified by means 

 of various medicinal agents which act upon the nervous system, 

 thus producing a sort of mixed action — voluntary and invol- 

 untary. For example; all medicines known as sedatives 

 operate so as to depress the heart's action, and lessen for a 

 given period the number of its pulsations ; while on the other 

 hand stimulants augment the action of the heart, and increase 

 the number of its pulsations. 



The average weight of the heart of an ox is eight pounds, 

 yet it is frequently the seat of fatty degeneration, when its 

 weight and bulk is then materially increased. 



