158 



STRUCTURE AND ENDOWMENTS OF ANIMAL TISSUES. 



in the foregoing manner ; and we shall commence with Adipose or 

 Fatty tissue, which may be considered as a sort of link, connecting the 

 permanent tissues with those which are more actively concerned in the 

 processes of Nutrition, Secretion, &c. 



Fig. 35. 



Fig. 36. 



Fusiform tissue of plastic 

 exudations; a, fusiform bo- 

 dies without nuclei ; 6, nu- 

 cleated fusiform cells; c, 

 granular intercellular sub- 

 stance. 



Areolar and Adipose tissue ; a, a, 

 fat-cells; 6, b, fibres of areolar 

 tissues. 



257. The Adipose tissue is composed of isolated cells, which have the 

 power of appropriating fatty matter from the blood, precisely in the 

 same manner as the secreting cells appropriate the elements of bile, milk, 

 &c. These cells are sometimes dispersed in the interspaces of the Areolar 

 tissue ; whilst in other cases they are aggregated in distinct masses, 

 constituting the proper Adipose tissue. In the former case they are 

 held in their places by fibres, that traverse the areolse in different direc- 

 tions ; whilst in the latter, each small cluster of fat-cells is included in 

 a common envelope, on the exterior of which the blood-vessels ramify ; 

 and these sacculi are held together by areolar tissue. We are thus 

 probably to regard each fatty mass in the light of a gland, or assemblage 

 of secreting cells, penetrated by blood-vessels, and bound together by 

 fibrous tissue ; but having its follicles closed instead of open (which 

 appears to be the early condition of the follicles of all glands, 238): 

 and consequently retaining its secretion within itself, instead of pouring 

 it forth into a channel for excretion. 



Capillary network around Fat-cells. 



258. The individual fat-cells always present a nearly spherical or sphe- 

 roidal form ; sometimes, however, when they are closely pressed together, 



