930 METABOLISM. 



are they due to any toxic substance accumulating in the blood (from 

 which it might be supposed to be normally removed by the pancreas), 

 as has been thought to be the case in the analogous instances of thyroid 

 and suprarenal extirpation, for the blood of an animal rendered diabetic 

 by pancreatic removal is not found to render a normal animal diabetic. 



The facts clearly show that the diabetes which results from pancreatic 

 extirpation is not the result of any interference with the sympathetic nerves 

 in the neighbourhood of the organ, nor is it due to the arrest of the passage 

 of the secretion of the gland into the intestine, but is exclusively the result 

 of the removal of something belonging to the gland which acts in independ- 

 ence of its functions in connection with digestion. Since we find in the 

 pancreas, if we compare its structure with^ similar glands such as the salivary, 

 that the only important difference is the occurrence in the parenchyma of the 

 pancreas of certain cell islands of an epithelium-like appearance richly supplied 

 with blood vessels, and entirely unconnected with alveoli or gland ducts, it 

 seems reasonable to suppose that the influence, whatever it may be, which the 

 pancreas exerts upon carbohydrate metabolism, and which results in the 

 excessive formation of sugar on its removal, is due to this particular tissue. 1 



That the salivary glands have no such influence upon metabolism as the 

 pancreas was shown by Fehr, 2 and also conclusively by Minkowski, 3 who, after 

 removal in dogs of all the salivary glands, including the orbital glands, found 

 no appreciable effects either upon carbohydrate or any other form of metabolism 

 to follow the removal. I have myself, in conjunction with Moore, repeated this 

 experiment in a dog, removing in successive operations all the salivary glands 

 upon both sides, leaving, however, the orbital glands. The animal remained 

 in perfect health for several months, and no disturbances could be determined 

 in either carbohydrate or proteid metabolism. 4 



METABOLISM OF FAT. 



Is the fat of the body directly derived from the fat of the food ? 

 That the fat of the body should be derived from the fat of the food 

 seems at first sight extremely probable. But, on consideration, it will 

 appear that before it is laid down as the fat of the tissues it would 

 probably undergo a change. For the fat of different animals has by 

 no means the same composition. Whereas some, such as the dog and 

 man, have a large amount of olein in their adipose tissue, and conse- 

 quently their fat has a comparatively low melting point, others, such as 

 the sheep, have a large proportion of stearin, and the fat of such animals 

 has a relatively high melting point. 



Now, if a dog or a man is fed upon sheep's flesh and fat, the fat 

 which is laid up in the body has not a different composition from that 

 which it ordinarily possesses. That is to say, a man living upon mutton 

 will have his body-fat, not of the consistency of mutton suet, but of the 

 ordinary consistency of the fat of the human body, having a melting 

 point far lower and containing a much larger amount of olein in its 

 composition. 



If, therefore, the fat of the food is laid down as the fat of the body, 

 it must undergo important modifications. It is possible to suppose that 

 only such portions of the fat of the food as would make fat of the 



1 Schafer, "On Internal Secretions," Brit. Med. Journ., London. August 1895. 



2 Inaug. Diss., Giessen, 1862 (quoted from Minkowski). 



:! Arch.f. exper. Path. u. FharmakoL, Leipzig, 1893, Bd. xxxi. S. 141. 



4 "Proc. Physiol. Soc.," Journ. PliysioL, Cambridge and London, 1896, vol. xix. p. xiii. 



