286 



THE TISSUES. 



Fig. 182. 



elements, just described. (Fig. 182.) They consequently have no 

 distinct walls, and they freely communicate with each other. Their 

 size varies extremely; sometimes occupying much more space in 

 the aggregate than the solid portions, in which case the tissue is 

 very loose ; while in other cases they are very small, from a con- 

 densation of the fibres around them. It is this free communication 



which* accounts for the ready diffusion 

 of blood and other fluids in the areolar 

 tissue under the influence of gravity. 

 The smallest meshes, however, in some 

 parts are so disposed as to constitute 

 secondary cavities of a somewhat de- 

 terminate shape and size, and which 

 are visible to the naked eye. These 

 generally contain fat-cells; and the 

 much-branched, sometimes tubular, 

 sometimes fissure-like spaces connect- 

 ing them, are termed the areolar pas- 

 sages. 



The contents of the areolae are : (1), a 

 fluid of an alkaline reaction, resem- 



11 wpa l r qpriim or (9\ fflt pplk 



its larger meshes. Each lamina and filar * \* lat-CCllS. 



ment here represented, contains numer- This fluid is a mere transudation, and 



not a secretion, from the bloodvessels 

 traversing the tissue, and its general 

 composition has been specified on page 



181. In some parts, however, the areolae are partly or entirely filled 

 by fat-cells; in which case the serous fluid is proportionately ex- 

 cluded. This is especially the case with the subcutaneous areolar 

 tissue, or superficial fascia. But in certain parts, fat never accu- 

 mulates; as underneath the skin of the eyelids, of the scrotum, &c. 

 The amount of fluid in the areolas is liable to sudden increase or 

 diminution, often from slight causes ; the former producing oedema 

 or swelling, and the latter a shrivelled appearance of the skin over 

 the part in which it occurs. 



Sometimes the areolse become filled to a greater or less extent 

 with air, to the exclusion of the fluid. Occurring as a pathological 

 condition it constitutes emphysema. This may, indeed, be produced 

 with the blowpipe experimentally ; and Bichat tells of mendicants 

 who excite the commiseration of passers-by, by the singular ap- 



Portion of areolar tissue, inflated and 

 dried, showing the general character of 



ous smaller ones, matted together by the 

 mode of preparation. (Magnified 20 dia- 

 meters.) 



