3l6 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787. 



found principally oti the outside of the muscles, immediately under the skin, and 

 is in considerable quantity. It is rarely to be met with in the interstices of the 

 muscles, or in any of the cavities, such as the abdomen or about the heart. In 

 animals of the same class living on land, the fat is more diftused: it is situated, 

 more especially when old, in the interstices of muscles, even between the fasci- 

 culi of muscular fibres, and is attached to many of the viscera ; but many part, 

 are free from fat, unless when diseased, as the penis, scrotum, testicle, eyelid, 

 liver, lungs, brain, spleen. &c. 



In fish its situation is rather particular, and is most commonly in 2 modes; in 

 the one, diffused through the whole body of the fish, as in the salmon, herrings 

 pilchard, sprat, &c.; in the other, it is found in the liver only, as in all of the 

 ray kind, cod, and in all those called white-fish, there being none in any other 

 part of the body *, The fat of fish appears to be diffused through the substance 

 of the parts which contain it, but is probably in distinct cells. In some of these 

 fish, where it is diffused over the whole body, it is more in some parts than 

 others, as on the belly of the salmon, where it is in larger quantity. 



The fat is differently inclosed in different orders of animals. In the quadruped, 

 those of the seal kind excepted, in the bird, amphibia, and in some fish, it is 

 contained in loose cellular membrane, as if in bags, composed of smaller ones 

 by which means the larger admit of motion on one another, and on their con- 

 necting parts; which motion is in a greater or less degree, as is proper or useful. 

 Where motion could answer no purpose, as in the bones, it is confined in still 

 smaller cells. The fat is in a less degree in the soles of the feet, palms of the 

 hands, and in the breasts of many animals. In this order of animals and the 

 seal kind, as far as I yet know, it is disposed of in '1 ways; the small quantity 

 found in the cavities of the body, and interstices of parts, is in general disposed 

 in the same way as in quadrupeds ; but the external, which includes the principal 

 part, is inclosed in a reticular membrane, apparently composed of fibres passing 

 in all directions, which seem to confine its extent, allowing it little or no motion 

 on itself, the whole, when distended, forming almost a solid body. This how- 

 ever is not always the case in every part of animals of this order; for under the 

 head, or what may be rather called neck, of the bootle-nose, the fat is confined 

 in larger cells, admitting of motion. This reticular membrane is very fine in 

 some, and very strong and coarse in others, and even varies in different parts of 

 the same animal. It is fine in the porpoise, spermaceti, and large whalebone 

 whale; coarse in the grampus and small whalebone whale -f-: in all of them it is 

 finest on the body, becoming coarser towards the tail, which is composed of 



* The sturgeon is however an exception, having its fat in particular situations, and in the inters- 

 tices of parts, as in other animals. — Orig. 



f Where it is fine, it yields the largest quantity of oil, and requires the least boiling. — Orig. 



