122 VETERINARY STATE BOARD 



Describe the action of salt in digestion. 



Salt increases thirst and causes the animal to drink more water, 

 which increases the fluidity of the food and thereby aids digestion 

 and absorption. In the stomach, it forms hydrochloric acid, which 

 is so essential to gastric digestion. 



Describe several conditions that retard digestion. 



Improper teeth cause improper mastication of the food, which 

 hinders the action of the digestive fluids. Improper foods (too hot, 

 too bulky, too cold, too dry, etc.) retard digestion. Feeding hay 

 before grain causes a retention of the latter in the stomach, and 

 disease conditions of any part of the alimentary canal retard or 

 entirely prevent digestion. 



Absorption 



Describe the lymph as to (a) appearance, (b) source, (c) function. 



(a) A transparent, slightly yeUow-colored fluid, alkaline in reac- 

 tion; occasionally it is a light rose color from the presence of red 

 blood-corpuscles, and it is often opalescent from the presence of 

 fat globules. 



(b) There are two theories advanced to account for the for- 

 mation of lymph. The more generally accepted one is the physical 

 theory. According to this, the lymph is formed from the blood by 

 the process of filtration and osmosis. The second or secretory theory 

 is based on the secretory activity of the endothelial lining of the 

 capillary walls. 



(c) Lymph is a sort of mediary material between the tissues and 

 the blood, by which nourishment is carried from the blood to the 

 tissues and effete material taken back to the blood. Generally 

 speaking, the lymphatic system is the drainage system of the body 

 as contrasted with the blood, the irrigating system. 



Describe the lymph-spaces, the lymph-capillaries and the general 

 arrangement of the lymphatic vessels. 



The lymph-spaces are irregular cavities, lined by epithelioid 

 plates, found in the connective tissue outside of the blood-vessel 

 walls, into which the lymph passes from the blood. From these 

 spaces, the lymph reaches the lymph-capillaries. The latter are 

 the most minute branches of the lymphatic vessels and their lining 

 is composed of the same epithelioid plates as found in the spaces. 

 Between these plates, crevices are supposed to exist through which 

 the lymph transudes. 



The lymphatic vessels follow the capillaries. They have, in addi- 

 tion to the epithelioid lining, a muscular coat and a connective-tissue 



