FATS. 259 



and starch ; but, as we have already observed, (p. 33 3 ) there are 

 no grounds for reckoning butyric acid among the fats, and the 

 formation of metacetonic, acetic, and formic acids, may just as well 

 be regarded as processes of the formation of fat, as that of butyric 

 acid. We are, therefore, for the present, constrained to regard 

 this view as a mere fiction, illustrated by chemical symbols, since, 

 whatever corroboration it may acquire from future experiments, it 

 is at present wholly devoid of all scientific support. 



Uses. We may regard the application of fat in the animal 

 body as conducive to mechanico-anatomical, to physico-physiolo- 

 gical, and chemico-physiological objects. 



The uses of the fat deposited in the areolar tissue of the animal 

 body are almost entirely of a strictly physical nature. If we reflect 

 that fat is mostly found in a fluid state during life, we shall per- 

 ceive some of the most useful properties which this condition im- 

 parts to the animal body. For although fat is enclosed in separate 

 layers and cells, it possesses so great a degree of mobility as to 

 propagate pressure equally in all directions in the same manner as 

 water. Every physicist knows that a bladder perfectly filled with 

 water cannot be brought to assume any given form without burst- 

 ing ; but we know that pressure applied to any part of such a 

 body will be equally propagated in all directions. If, therefore, we 

 suppose a number of such bladders to be laid side by side, enclosed 

 in a larger space, and that we press one of them, the pressure thus 

 applied will be propagated to all the others ; and here we have an 

 illustration of the uniform diffusion of external pressure through the 

 whole adipose tissue. But besides the protection thus afforded the 

 body from external shocks, it is further guarded in leaping and 

 falling by the Haversian glands, which penetrate into the joints, and, 

 receiving the shock, propagate it over a larger surface, by which 

 its violence at each individual point must be very much diminished. 

 Such was the object of nature in placing layers of fat on the soles 

 of the feet, and the tuberosities of the Ischium ; and thus the 

 depositions of fat were made to answer the purpose of water-cushions 

 and other inventions of man's ingenuity, for the promotion of his 

 ease and comfort. 



Haller was the first who drew attention to the extreme 

 utility of fat in filling up those interstices which must unavoidably 

 exist between muscles, bones, vessels, and nerves. The bodies 

 of children and women principally own their rounded forms 

 to the deposition of fat in the subcutaneous cellular tissue. The 

 extreme mobility of the separate organs and parts of organs is 



s 2 



