26 INTRODUCTION. 



the number but the nature of these contractions, whether propelling^ 

 a greater or smaller quantity of blood. By the number and the force 

 of the pulsations the decrree of fever is indicated with considerable 

 certainty. The heat of the mouth, and of the base of the horns, will 

 be important guides; but a much safer one, and more clearly ascer- 

 taining the extent and the nature of the fever, is the action of the 

 heart faithfully represented by the pulse. Wherever the finger can 

 be placed on an artery that is not too thickly covered by cellular 

 membrane or fat, and that has some firm substance beneath, the 

 pulse may be felt; but most conveniently so where, at the back part 

 of the lower jaw, the artery comes from the channel between the 

 jaws, and passes over the edge of the jaw-bone, to ramify on the 

 face. 



The natural pulse of the full-grown ox varies from 50 to 55 beats 

 in a minute, but is quicker in milch cows than in oxen, and particu- 

 larly towards the period of parturition. A pulse much quicker than 

 that here stated denotes fever or inflammation; whilst one much 

 slower indicates sluggishness of the circulation, or debility. 



There are other circumstances, however, to be taken into the ac- 

 count, — as the force or the weakness of the heart's action, — strong 

 and bounding at the beginning of inflammatory fever, and weak and 

 scarcely to be felt when that fever is assuming a putrid form. The 

 regularity or irregularity of the pulse is also an important considera- 

 tion as characterising the kind of irritability under which the heart 

 labours. They who have to do with cattle will find it of immense 

 advantage to study the pulse, and especially in reference to the pro- 

 priety of bleeding; for a large bleeding will, in some cases, cut the 

 disease short at once, while at other times it would destroy the re- 

 maining strength of the animal, and ensure and hasten its death. 



The blood flows through the arteries principvilly by the impulsive 

 power of the heart. The arteries, however, possess a controlling in- 

 fluence independent of the heart, and can, imder circumstances of 

 necessity or disease, supply a deficiency of action in the heart, or 

 neutralize its too violent elForts. 



At the termination of the arteries, and branching from them at every 

 point of their course, are other vessels as small as a hair, or a thou- 

 sand times smaller, through which the blood must find its way. 

 These are the capillaries,' and in them, or in the glands into which 

 they enter, or which they compose, all the important offices of secre- 

 tion and nutrition are performed. These offices being discharged, 

 and the various portions of the frame being built up, the blood has 

 materially changed. From being of a scarlet colour it has become 

 black — from being capable of supporting life it is poisonous — from 

 arterial it is changed to venous — and, these capillary vessels running 

 into each other and gradually enlarging, we begin to recognise the 

 veins. The veins commence where the arteries terminate, and by 

 them the black blood is collected, and carried back to the heart, to be 

 thence pumped into the lungs, for the purpose of re-purification. 



