484 A MANUAL OF PHYSIOLOGY 



metabolism of the body, it is impossible to doubt, in view of 

 the facts we have mentioned, that both of these organs, like 

 the liver, in addition to carrying on the exchanges necessary 

 'for the preparation of their ordinary or external secretions, 

 have other important relations with the circulating fluids, 

 giving to them or taking from them substances on the manu- 

 facture or destruction of which the normal metabolic pro- 

 cesses depend. Schafer has suggested that the seat of the 

 internal secretion of the pancreas is the very vascular epithe- 

 lioid tissue which is peculiar to this gland, and occurs in 

 islands between the alveoli. For animals survive the complete 

 atrophy of the ordinary secreting epithelium caused by the 

 injection of paraffin into the ducts ; no sugar appears in the 

 urine, and the grafting of such an atrophied organ prevents 

 pancreatic diabetes. 



Ligation, or the establishment of a fistula, of the thoracic 

 duct, causes glycosuria in dogs. It is possible that this 

 is really a mild form of pancreatic diabetes, due to inter- 

 ference with the supply of the internal secretion of the pan- 

 creas, or of that part of it which reaches the blood by the 

 lymph-stream (Tuckett). 



Sexual Organs. The influence of castration in preventing 

 the physical and psychical changes that normally occur at 

 puberty is no doubt also, in part at least, due to the loss of 

 the internal secretion of the testes, In partially castrated 

 cocks it was seen that so long as a portion of one testicle 

 remained, the male characters were preserved, but after 

 removal of this residue the comb and wattles withered in a 

 few weeks (Hanau). The exact experiments of Loewy and 

 Richter on the metabolism of bitches before and after castra- 

 tion throw light upon the changes which follow that opera- 

 tion, and afford decisive proof that they are connected with 

 the absence of substances specific to the ovary. They conclude 

 that in the castrated animal the oxidative energy of the cells 

 is lessened. The oxygen consumption sinks, even although 

 proteid is laid on and the total amount of active tissue thus 

 increased. This lessening of the oxidative power is due to 

 the loss of ovarian substance, for the administration of an 

 extract of the ovary (oophorin) not only neutralizes it, but 

 actually causes an increase in the gaseous metabolism to far 



