APPETITE. 55 



length is about 20 feet. The caecum appears to be a 

 kind of supplementary stomach, in which is collected 

 the pulpy mass of still unassimilated food, mixed with 

 the water, which the stomach and small intestines failed 

 to take up. Here the remaining nutritive particles are 

 dissolved out and absorbed. The caecum can contain 

 about 7-J gallons of fluid. 



Functions performed by the Blood. A.S the nutritive 

 part of the food becomes changed into forms capable of 

 being assimilated, it becomes gradually taken up by the 

 minute vessels called absorbants that line the interior of 

 the stomach and intestines, and is conveyed- into the 

 blood, which ramifies through the various tissues of 

 the body, supplying them with materials for repair. 

 Thus we see that the blood acts as the vehicle for remov- 

 ing the products resulting from the waste of tissue, and 

 also for furnishing the elements required in the building 

 up of new structures. 



Appetite. Appetite serves two purposes (1) When 

 the system requires new elements for repair, it prompts 

 the animal to eat, so as to obtain them from his food. But, 

 in order to avoid excess, the process of feeding should 

 be carried on slowly. On this subject, Dr. Carpenter 

 remarks " To eat when we are hungry, is an evidently 

 natural disposition ; but to eat as long as we are hungry, 

 may not always be prudent. Since the feeling of hun- 

 ger does not depend so much upon the state of fulness 

 or emptiness of the stomach, as upon the condition of 

 the general system, it appears evident that the ingestion 

 of food cannot at once produce the effect of dissipating 

 it, though it will do so after a short time ; so that, if 



