VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. 3l7 



fibres without any fat: which is also the case in the covering of the fins. This 

 reticular net -work in the seal is very coarse; and in those which are not fat, when 

 it collapses, it looks almost like a fine net with small meshes. This structure 

 confines the animal to a determined shape, whereas in quadrupeds fat when in 

 great quantity destroys all shape. 



The fat differs in consistence in different animals, and in different parts of the 

 same animal, in which its situation is various. In quadrupeds, some have the 

 external fat softer than the internal; and that inclosed in bones is softest nearer 

 to their extremities. Ruminating animals have that species of fat called tallow* 

 and in their bones they have either hard fat or marrow, or fluid fat called neat's- 

 foot oil. In this order of animals, the internal fat is the least fluid, and is nearly 

 of the consistence of hog's-lard; the external is common train oil; but the sper- 

 maceti whale differs from every other animal I have examined, having the 2 kinds 

 of fat just mentioned, and another which is totally different, called spermaceti, 

 of which I shall give a particular account. 



What is called spermaceti is found every where in the body in small quantity, 

 mixed with the common fat of the animal, bearing a very small proportion to 

 the other fat. In the head it is the reverse, for there the quantity of spermaceti 

 is large when compared to that of the oil, though they are mixed, as in the other 

 parts of the body. As the spermaceti is found in the largest quantity in the 

 heady and in what would appear on a slight view to be the cavity of the skull, 

 from a peculiarity in the shape of that bone, it has been imagined by some to be 

 the brain. These 2 kinds of fat in the head are contained in cells, or cellular 

 membrane, in the same manner as the fat in other animals; but besides the com- 

 mon cells there are larger ones, or ligamentous partitions going across, the better 

 to support the vast load of oil, of which the bulk of the head is principally made 

 up. There are 2 places in the head where this oil lies; these are situated along 

 its upper and lower part: between them pass the nostrils, and a vast number of 

 tendons going to the nose and different parts of the head. The purest spermaceti 

 is contained in the smallest and least ligamentous cells: it lies above the nostril, 

 all along the upper part of the head, immediately under the skin, and common 

 adipose membrane. These cells resemble those vvhich contain the common fat in 

 the other parts of the body nearest the skin. That which lies above the roof of 

 of the mouth, or between it and the nostril, is more intermixed with a ligamentous 

 cellular membrane, and lies in chambers whose partitions are perpendicular. These 

 chambers are smaller the nearer to the nose, becoming larger and larger towards 

 the back part of the head, where the spermaceti is more pure. This spermaceti, 

 when extracted cold, has a good deal the appearance of the internal structure of 

 a water melon, and is found in rather solid lumps. 



About the nose, or anterior part of the nostril, I discovered a great many 



