94 THE CONNECTIVE TISSUES, BY A. ROLLETT. 



tint in man, but in various animals many other tints occur. In 

 the fresh cells, both of cold and warm-blooded animals, the fat 

 is fluid. On cooling, it solidifies with great facility, especially 

 in the latter class of animals. This last process occasions a 

 flattening of the closely compressed cells, and their oily contents 

 may frequently be observed to crystallize partially in needles 

 which are collected in the form of a brush. When this occurs, 

 a single spicule or a crystalline stella, composed of many 

 spicules, appears on the surface of the fat cells* 



Besides the large fat cells enclosed in a smooth membrane, 

 which are most abundant in fully developed adipose tissue, 

 other cells also occur which are smaller, and in which the oil 

 drops are invested by a layer of granular cell substance ; this, 

 when seen in profile, appears in the form of a rather broad ring 

 around the oil drop. Cells presenting this aspect are frequently 

 found at the borders of fat lobules, as in newly formed adipose 

 tissue, whether in the embryo or in the adult. The formation 

 of adipose tissue may be excellently followed in the omentum 

 of animals as well as in certain cases of sudden death in man. 

 In the first stage of their development, the cells that subse- 

 quently form fat cells appear as small round granular bodies, 

 provided with round nuclei, and presenting all the characters of 

 young cells. In the interior of these a few small strongly re- 

 fractive oil drops first originate, which, however, usually soon 

 collect to form a single large fat drop, occupying the middle of 

 the cell. Much less frequently several large drops are found 

 close to one another. 



The protoplasm of the cells in which such large drops have 

 developed, lies like a cincture around the drops, presenting 

 everywhere nearly the same breadth, except only where the 

 nucleus is imbedded in it and forms a thickening or projection 

 that causes the whole protoplasmic mass to be comparable to 

 a signet ring. 



During the succeeding stages of development the cells 

 undergo continuous increase in size, the oil drops in par- 

 ticular becoming larger. The investing protoplasmic layer, 

 whilst it progressively diminishes, though not proportionately 



* Henle, Allgemeine Anatomie, p. 393. 



