72 CHEMICAL COMPONENTS OF THE HUMAN BODY. 



by macerating a piece of muscle in water, as has been proved by various experi- 

 menters. 1 This conversion of protein-compounds into fatty matters, however, 

 must always be looked upon as a pathological change, when it occurs in the tis- 

 sues ; but its spontaneous occurrence must be admitted as valid evidence, that 

 the fat which is generated in the liver may be formed out of the products of the 

 disintegration of the albuminous tissues, or even by the metamorphosis of the 

 albuminous elements of the food. 3 In one of these two modes it seems evident 

 that the liver-fat must be formed in Carnivorous animals ; but in the Herbivora 

 its materials will be more readily furnished by the saccharine alimentary mat- 

 ters. 



41. The importance of these Fatty matters in the Animal economy must not 

 be estimated merely by the proportion of its fabric that is made up of Adipose 

 tissue, the cells of which are filled with a mixture of Margarin (in man), or of 

 Stearin (in most other animals), with Olein. For it is next to certain that the 

 nutrition of Nervous tissue is effected in great degree at their expense, although 

 the precise composition of that tissue, and its chemical relations to the histo- 

 genetic substances, have not yet been elucidated. And we shall find that their 

 presence in the Chyle and Blood has probably a no less intimate relation to the 

 general processes of Nutrition, than it has to the formation of the tissues of 

 which it is the more especial pabulum. Further, a considerable proportion of 

 the fatty matters introduced into the nutritious fluids of warm-blooded animals, 

 never forms part of their tissues at all, but is at once removed by a process 

 essentially resembling combustion, on which the maintenance of the heat of the 

 body is dependent. The amount of fatty matter in the Chyle depends in great 

 part upon the nature of the food, being larger in proportion as the digested 

 aliment has contained a greater abundance of it ; and its presence is indicated 

 by the milky opacity that distinguishes this fluid from Lymph, to which in 

 other respects it bears a close resemblance. This milky opacity is not so much 

 due to the presence of the larger oil-globules, which are distinctly recognizable 

 as such with the aid of the microscope ; as it is to the diffusion of the fatty 

 matter through the whole liquid, in particles of such extreme minuteness that 

 their diameter can be scarcely measured, forming what has been termed by Mr. 

 Gulliver the "molecular base" of the chyle. The fatty matter of the Chyle is 

 for the most part unsaponified, and corresponds in its composition to that of 

 the ordinary salts of the oxide of lipyl. The amount of fat contained in the 



1 It has been supposed by some, that the presence of adipocere is sufficiently accounted 

 for by that of the fat previously contained in the muscular substance, and that the decom- 

 position of the proper muscular tissue has no share in its formation, except as furnishing 

 its base. This, however, is an untenable proposition. A body was exhumed at Bristol 

 some years since, which had been buried during the Civil War, and which appeared exter- 

 nally in a state of remarkable preservation, the flesh retaining much of the plumpness of 

 life ; and as this was in a state of complete saponification, it is obvious that the amount 

 of adipocere must have been far greater than the fat previously in the body would account 

 for. And besides, the structural form of the muscular tissue may be clearly made out in 

 adipocere produced by the action of water upon it. Further, it has been ascertained by 

 Blondeau (" Compt. Rend." torn. xxv. p. 360), that the casein of cheese undergoes a grad- 

 ual transformation into a saponifiable fat ; and that the same change takes place in fibrin 

 under similar circumstances. For an excellent summary of the evidence upon this sub- 

 ject, with various pathological and experimental illustrations, see the Memoir of Dr. R. 

 Quain on "Fatty Diseases of the Heart," in the " Medico-Chirurgical Transactions," vol. 

 xxxiii. 



2 Certain experiments of Boussingault upon ducks appear at first sight to favor the 

 idea that fat may be formed from albuminous substances during the digestive process ; 

 but, as has been pointed out by Lehmann (op. cit. vol. i. p. 258), these results are by no 

 means sufficient to prove the existence of so remarkable a transformation, since the fatty 

 matters found within the intestinal canal, when the birds had been fed on albumen and 

 casein containing little or no fat, may have been derived from the bile. 



