ADIPOSE TISSUE. 305 



6. Fat, by its low specific gravity, renders the human body lighter 

 than its bulk of water in proportion to its amount. Hence it is an 

 aid in swimming. 



7. Lastly, the fat in the adipose tissue may become useful as nu- 

 tritive material in cases of emergency ; the fat being reabsorbed 

 into the blood, and then becoming "fuel for respiration" (p. 77, 2). 



Fluid fat alone is, however, merely calorific, and will not long 

 sustain an animal (p. 76, 3). But adipose tissue, taken as food into 

 the stomach, will nourish for a long period, as demonstrated by 

 Magendie ; since it also contains albuminous elements in its cell : 

 walls, and osteine in its areolar tissue. The fact that all cells need 

 fat for their development, since all nucleoli consist of fat (Hune- 

 feld), has already been specified (p. 78, 5). Hence its necessity in the 

 blood whence it is also derived for the formation of bile and other 

 secretions (p. 77, 2). The use of fat in the food, as an aid to digestion, 

 has also been specified (p. 78, 5) ; and Lehmann suggests that the 

 pancreatic fluid owes its power in this respect to the fat it contains. 

 But in all these fluids we find mere fat-globules, and not fat-cells. 



Development of* Adipose Tissue. 



The adipose or fat-cell manifests no peculiarity in its develop- 

 ment. At first small and nucleated, it subsequently increases in 

 size, and its nucleus disappears. Kolliker never 

 fails to find the nuclei, however, when the cells are 

 only partially filled with fat ; and it must there- 

 fore be persistent. (Fig. 191.) 



The first lobules of fat appear in the fourth 

 month of intra-uterine life, in the palms of the 

 hands and the soles of the feet. The subcuta- 

 neous adipose tissue is rapidly developed from 



r r J r A fat-cell to show the 



the seventh month to birth. Hence the foetus at nucleus; from sch warm, 

 five or six months has a wrinkled condition of ^ieus 611 " 11 " * Nu " 

 the skin generally. 



Is the fat in the organism formed from fat alone in the food ? 

 There is reason to believe not only that starch, sugar, &c., may be 

 converted into fat in the organism, to a very slight extent, but that 

 even from albumen also fat may be formed in small quantity in the 

 alimentary canal (p. 74). Still, neither of these two points can be 

 regarded as established. (Lehmann?) 



1 Physiological Chemistry, vol. i. pp. 230-32. 

 20 



