METABOLISM, NUTRITION AND DIETETICS 553 



nor denied to all other organs. For the salivary, mammary, 

 and gastric glands may be completely removed without causing 

 any serious effects, while death follows excision of the, so far as 

 mere bulk is concerned, apparently insignificant masses of tissue in 

 the ductless thyroid, parathyroid, suprarenal or pituitary bodies. 



It is known that in the case of the liver the internal secretion 

 is more important than the external, for an animal cannot 

 survive without its liver, while it may be but little affected by 

 the continuous escape of the bile through a fistulous opening. 



Pancreas. The internal secretion of the pancreas is also 

 indispensable. For when the pancreas is excised death follows 

 in many species of animals, and especially in carnivorous animals ; 

 and in man severe and ultimately fatal diabetes is often associated 

 with pancreatic disease, while the mere loss of the pancreatic 

 juice through a fistula does not necessarily shorten life, although 

 the absorption of fat is seriously interfered with. 



The ultimate cause of death seems to be a profound disturbance 

 of metabolism, of which the most significant token is the in- 

 creased proportion of sugar in the blood, and its speedy appear- 

 ance in the urine in dogs always within twenty-four hours 

 following total removal of the organ. Associated with the 

 glycosuria is an increase in the quantity of the urine (polyuria) , 

 excessive thirst (polydipsia), and a ravenous appetite (poly- 

 phagia), in spite of which the animal becomes more and more 

 emaciated in short, the classical symptoms of a severe type of 

 pathological diabetes in man, but, of course, far more acute in 

 their onset, and far more rapid in their progress towards the 

 inevitable end. Dogs rarely survive more than two or three 

 weeks, the immediate cause of the rapidly fatal result being 

 perhaps the extensive suppuration which is apt to ensue on 

 slight and practically unavoidable superficial injuries. The 

 resistance of the tissues to bacterial invasion and their tendency 

 to spontaneous healing are reduced by the overloading of the 

 blood and tissue liquids with sugar. Even when carbo-hydrates 

 are excluded from the food, or when no food at all is given, 

 sugar continues to be excreted in large amounts. The destruction 

 of proteins is increased. It is a significant fact that glycosuria 

 does not appear or is only transient when the pancreas is partially 

 removed, so long as a comparatively small fraction of the gland 

 (one-quarter or one-fifth) is left. Even when such a remnant 

 is transplanted from its original position, care being taken not 

 to interfere with its circulation, and grafted in the peritoneal 

 cavity or, indeed, under the skin, the animal remains in good 

 health. In the dog this operation can be practised on the 

 lowest part of the descending division of the pancreas, which is 

 not united with the duodenum, but lies free in the mesentery. 



