ANATOMY OF ADIPOSE TISSUE. 387 



ments of fat are, carbon, hydrogen, and oxygen, the two 

 latter in unequal proportions. It has been found very diffi- 

 cult, however, to obtain either stearin e, margarine, or oleine 

 in a condition of sufficient purity to ascertain their exact 

 ultimate composition. 1 



Physiological Anatomy of Adipose Tissue. Adipose 

 tissue is found in abundance in the interstices of the sub- 

 cutaneous areolar tissue, where it is sometimes known as the 

 panniculus adiposus. It is not, however, to be confounded 

 with the so-called cellular or areolar tissue, and is simply 

 associated with it without being one of its essential parts ; 

 for the areolar tissue is abundant in certain situations, as the 

 eyelids and scrotum, where there is no adipose matter, and 

 adipose tissue exists sometimes, as- in the marrow of the 

 bones, without any areolar tissue. 



Adipose tissue is widely distributed in the body, and has 

 important mechanical functions. 2 Its anatomical element is 

 a vesicle, from -g-i-g- to -g-fj of an inch in diameter, composed 

 of a delicate, structureless membrane, 2g ^ 00 of an inch 

 thick, enclosing fluid contents. 3 The form of the vesicles is 

 naturally rounded or ovoid ; but in microscopical prepara- 

 tions they are generally compressed so as to become irregu- 

 larly polyhedrical. The membrane sometimes presents a 

 small nucleus attached to its inner surface. The contents 

 are a minute quantity of an albuminoid fluid moistening the 

 internal surface of the membrane, and a mixture of oleine, 

 margarine, and stearine, liquid at the temperature of the 

 body, but becoming harder on cooling.* Little rosettes 

 formed of acicular crystals of margarine are frequently ob- 

 served in the fat- vesicles, when the temperature is rather low. 



1 ROBIN* ET VERDEIL, Traite de chimie anatomique et phwiologique, Paris, 1853, 

 tome iii., p. 105. 



2 See vol. i., Introduction, p. 65. 



3 LITTRE ET ROBIN*, Didionnaire de medecine, Paris, 1865, Article, Adipeiix. 



4 TODD AND BOWMAN, Physiological Anatomy and Physiology of Man, Phila- 

 delphia, 1857, p. 89. 



