ADIPOSE TISSUE. 



57 



tig-nous cellular tissue without leaving any trace 

 of their existence. 



Hunter, however, asserts that in such cir- 

 cumstances the cellular tissue differs from the 

 tissue of adipose vesicles in containing no 

 similar cavities, remarks that the latter is much 

 more fleshy and ligamentous than the fila- 

 mentous tissue, and contends that though the 

 adipose vesicles are empty and collapsed, they 

 still exist. When the skin is dissected from 

 the adipose membrane, it is always possible 

 to distinguish the latter from the filamentous 

 tissue, even if it contain no fat, by the tough- 

 ness of its fibres and the coarseness of the web 

 which they make. 



The distinguishing characters between the 

 cellular or filamentous and the adipose tissue 

 may be stated in the following manner. First, 

 the vesicles of the adipose membrane are closed 

 all round, and, unlike the cellular tissue, they 

 cannot be generally penetrated by fluids which 

 are made to enter them. If the temperature 

 of a portion of adipose membrane be raised 

 by means of warm water to the liquefying 

 point of the contents, they will remain un- 

 moved so long as the structure of the vesicles 

 is not injured by the heat. If again an adi- 

 pose packet be exposed to a solar heat of 104 

 Fahrenheit, though the fat be completely lique- 

 fied, not a drop will escape until the vesicles 

 are divided or otherwise opened, when it ap- 

 pears in abundance. The adipose matter, 

 therefore, though fluid or semifluid in the 

 living body, does not, like dropsical infiltra- 

 tion, obey the impulse of gravity. Secondly, 

 the adipose vesicles do not form, like cellular 

 tissue, a continuous whole, but are simply in 

 mutual contiguity. This arrangement is de- 

 monstrated by actual inspection, but becomes 

 more conspicuous in the case of dropsical effu- 

 sions, when the filamentous tissue interposed 

 between the adipose molecules is completely 

 infiltrated while the latter are entirely unaf- 

 fected. Thirdly, the anatomical situation of 

 the adipose tissue is different from that of the 

 filamentous tissue. The former is found, 1st, 

 in a considerable layer extended immediately 

 beneath the skin; 2dly, in the trunk and ex- 

 tremities round the large vessels and nerves ; 

 3dly, between the serous and muscular tissues 

 of the heart ; 4thly, between the peritoneal 

 folds which form the amentum and mesentery ; 

 Mlily, round each kidney; and, Gthly, in cer- 

 tain folds of the synovial membranes without 

 the articular capsules. 



In each of these situations it varies in quan- 

 tity and physical properties. In the least cor- 

 pulent persons a portion of fat is deposited in 

 the adipose membrane of the cheeks, orbits, 

 palms of the hands, soles of the feet, pulp of 

 the fingers and toes, flexures of the joints, 

 round the kidney, beneath the cardiac serous 

 membrane, and between the layers of the me- 

 sentery and amentum. In the more corpulent, 

 and chiefly in females, it is found not merely 

 in these situations, but extended in a layer of 

 some thickness, almost uniformly over the 

 "hole person; but is very abundant in the 



neck, breasts, belly, mons Veneris, and flexures 

 of the joints. 



It has been long observed that the subcu- 

 taneous adipose layer presents considerable 

 differences from the adipose matter found be- 

 tween the folds of the serous membranes ; and 

 the older anatomists, aware of these differences, 

 distinguished the former by the name of p'm- 

 guedo, and the latter by that of sebum. The 

 subcutaneous adipose membrane is, when 

 viewed as a whole, more elastic, softer, and 

 less granular than the omental fat, and evi- 

 dently presents the arrangement of vesicular 

 bags much more distinctly than the omental. 

 It is in the subcutaneous adipose membrane 

 indeed, almost exclusively, that the vesicular 

 arrangement can be recognized. The subcu- 

 taneous cellular fat also contains a greater 

 quantity of oil than the omental, which abounds 

 chiefly in firm, brittle, granular fat. 



The situation where the vesicular structure 

 of the adipose membrane is most easily de- 

 monstrated is in the hips between the skin 

 and the gluteal muscles, and at the flexur.es of 

 the joints generally. In the former situation 

 especially, the constituent fibres of the vesi- 

 cular bags are tough, firm, and ligamentous, 

 and the bags themselves are large and distinct. 



It is a remarkable anatomical character of 

 the sebaceous or tallow-like fat that its distri- 

 bution is confined chiefly to the external or 

 commutual surfaces of several of the serous 

 membranes; and this arrangement presents a 

 series of interesting anatomical analogies. Thus 

 sebaceous fat is found on the external surface 

 of the pleura castalis, between it and the inter- 

 costal muscles, and between the layers at the 

 posterior and anterior mediastinum. It is also 

 found between the cardiac pericardium and the 

 muscular substance of the heart, especially 

 around the vessels of the organ. In some of 

 the large mammalia even this circumstance is 

 connected with peculiar anatomical appear- 

 ances. Thus, in the heart of the dolphin (del- 

 phinus turuo) we find the cardiac pericardium 

 formed into broad prominent fringes, consisting 

 each of two folds of the membrane, between 

 which is interposed a considerable quantity of 

 sebaceous fat. In the same manner the several 

 amenta, or peritoneal duplicatures in the abdo- 

 men, may be recognized as analogous fringes 

 containing more or less sebaceous fat ; and the 

 omental appendages (appendices epiploicts) of 

 the colon must be regarded as examples of the 

 same arrangement. Lastly, in the interior of 

 the articular capsules we find the synovial 

 membranes forming large prominent fringes, 

 which, if immersed in water, show to what 

 extent they are made to recede from the cap- 

 sule and bone, and forming cavities of dupli- 

 cation in which sebaceous matter is contained. 

 It thus appears that none of the serous mem- 

 branes is exactly applied either to the parietes 

 of cavities or to the surface of the contained 

 organs, but that they form intervals on their 

 outer or attached surfaces, on which various 

 quantities of sebaceous fat are deposited. In 

 all these substances we do not recognize the 



