OF THE PURELY CELLULAR TISSUES. CARTILAGE. 259 



an extraordinary tendency to the development of Adipose tissue, which may 

 thus appropriate to itself the nutriment that is destined for the supply of other 

 parts ; and this sometimes shows itself throughout the body, constituting general 

 Obesity or Polysarcia, and sometimes in individual parts forming Lipoma or 

 fatty tumor. Although general Obesity is doubtless favored by the conditions 

 just referred to, yet it may develop itself under circumstances of a very different 

 kind; namely, when the food is neither rich nor abundant, when active exercise 

 is taken, and when the individual habitually exposes himself to a cool atmo- 

 sphere. And we cannot but here recognize the same kind of excessive develop- 

 mental power in the Adipose tissue, as shows itself locally in tumors, which 

 will even grow and increase when the body generally is in a state of extreme 

 emaciation. On the other hand, there are individuals in whom there is 

 an obvious deficiency in the power to generate this tissue ; since they never 

 become otherwise than lean, even under the most favorable conditions. Such 

 persons, moreover, are usually very apt to become " bilious" when they take in 

 much oleaginous matter with their food ; for if the surplus be not drawn off from 

 the blood in the generation of Adipose tissue, it is probably thrown for elimi- 

 nation upon the liver, which organ is very prone to be disordered by being called 

 into excessive functional activity. 



250. Besides the support, combined with facility of movement, which Fat 

 affords to the moving parts of the body, it answers the important purpose of 

 assisting in the retention of the animal temperature, by its non-conducting 

 power; and the still more important object, of serving as a kind of reservoir of 

 combustible matter against the time of need. Herbivorous animals, whose food 

 is scanty during the winter, usually exhibit a strong tendency to such an accu- 

 mulation, during the latter part of the summer, when their food is most rich and 

 abundant ; and the store thus laid up is consumed during the winter. This is 

 particularly evident in the hybernating Mammalia, which take little or no food 

 during their seclusion. Again, when Birds or Mammals are deprived of food, 

 the duration of their lives is proportional, cseteris paribus, to the amount of fat 

 they contain ; the immediate cause of death in such cases being the reduction 

 of the temperature of the body, which takes place as soon as the store, of com- 

 bustible material is exhausted (CHAP. xni.). If there were no such store within 

 the system, we should be dependent upon a constant supply of aliment for our 

 heat-producing power ; and the loss of even a single meal might be fatal. This 

 condition is seen in animals which have been brought to the verge of starvation, 

 and which are only at first capable of digesting a small quantity of food ; for, 

 as Chossat's experiments have shown, until they have in some degree replaced 

 their fat by the assimilation of surplus nutriment, they cannot sustain life except 

 by the assistance of artificial heat. 1 



251. In Cartilage, also, the simple cellular structure is very obviously re- 

 tained, and frequently exists alone ; although in some forms of this tissue, it is 

 united with the fibrous, or is partly replaced by it. In all, however, the early 

 stage of formation appears to be the same. The structure originates in cells, 

 analogous to those of which the rest of the fabric is composed ; but between 

 these cells, a large quantity of hyaline or intercellular substance, consisting of 

 Chondrin ( 34), is soon deposited ; and the amount of this substance usually 

 continues to increase simultaneously with the bulk of the cells. The original 

 cells are pushed farther and farther from one another ; but new cells arise 

 between them, from germs which are contained in the hyaline substance. The 

 first cells frequently produce two or more young cells by subdivision ( 104), 

 and this act may be repeated ; and thus it is very common to meet with groups 

 of such cells or corpuscles, consisting of two, three, or four (Fig. 51). These 



1 See his " Recherches Experimentales sur 1'Inanition." 



