THE BONY TRUNK. 73 



size of the lungs ; and the very tooth itself, in spite of its 

 hardness, gives way before the pressure of the newly formed 

 organ, which as yet is incapable of doing any work, never 

 having seen the light. As the new tooth shoots up the 

 fang of the incisor is absorbed, and when it is entirely re- 

 moved of course the crown falls out of the mouth, leaving 

 a vacant space, which the new organ is destined to fill. 

 It is otherwise with the molars. When the fang of the 

 molar is absorbed, the temporary tooth does not fall 

 out, but the absorption is continued to the crown, a 

 great portion of which also is removed, leaving the grinding 

 surface as a protection to the new tooth. When this 

 grinding surface is, by the process of absorption, reduced 

 to great thinness, and the permanent molar is well up, or 

 into the mouth, the covering of the old tooth falls off, and 

 there is a new member fully formed and ready to supply 

 its loss. 



The reason of this is very apparent. A horse with four 

 nippers can gather enough food to support life ; but serious 

 ills would occur if a molar were absent, even for a single 

 day. The continued presence of the more important teeth 

 is thus provided for. 



The horse has been said to cut his teeth with ease, but 

 Mr. Percivall, in his lately finished work, entitled " Hippo- 

 pathology," records cases where the animal has been seri- 

 ously affected during the process of dentition. Nothing is 

 easier than to conclude those who are dumb undergo no pain ; 

 but any man, with proper feeling, has only to look into the 

 horse's mouth, at the time of shedding the teeth, and to 

 behold the swollen, inflamed, and bleeding condition of the 

 gums, to be convinced that Mr. Percivall's is the truer 

 statement. 



THE BONY TRUNK. 



The osseous structure of the trunk comprises the neck, 

 the back, the haunch, the ribs, and the breast bones. 



The neck consists of seven, the back of eighteen, the 

 loins of six, the top of the pelvis, or sacrum, of five, and 

 the tail, generally, of from thirteen to eighteen vertebrae, 

 or distinct bones ; the whole forming what is termed 

 the spine. The spinal bones are divided into different 



