ORGANS OF NUTRITION IN THE HORSE. 11 



vascular or blood glands the mesenteric glands rank, through 

 which the chyle passes in its progress from the small intestines 

 to the thoracic duct that conveys it to the venous blood. 



These blood-glands are supposed to be capable of secreting 

 the germs of vesicular organisms, which, coming into contact 

 with proteine compounds in the lymphatic and lacteal ves- 

 sels, and afterwards in the blood itself, pass into the red cor- 

 puscles of the blood. 



Thus nutrition in the higher animals would take place exactly 

 on the same type as in the simplest organisms in the scale of 

 being. The Protococcus nivalis, or red snow, is a simple cell which 

 becomes developed by drawing nourishment from a surround- 

 ing plasma or cytoblastema. The proteine compounds yielded 

 by the digestive organs to the lacteal vessels and blood corre- 

 spond to the cytoblastema of the red snow ; while the germs of 

 the blood corpuscles, and the organic atoms of the solids requir- 

 ing repair, correspond to the organic cell of the red snow. 



ORGANS OF NUTRITION IN THE HORSE. 



Mouth and Teeth. The mouth is the space included be- 

 tween the lips and the throat. In front, the muzzle being 

 supposed to be directed forward, it is bounded by the lips ; on 

 the sides by the cheeks ; below by the tongue; above, anteriorly, 

 by the bars of the hard palate posteriorly, by the soft palate ; 

 while behind it communicates with the pharynx, the funnel- 

 shaped cavity placed between the mouth and the gullet. 



Before describing the uses of these several parts, it will be 

 convenient to speak of the teeth, which occupy both jaws within 

 the lips arid cheeks. 



In the function of nutrition the teeth are of infinite import- 

 ance, as the agents in the indispensable office of mastication. 



