768 DIABETES. [BOOK n. 



frogs, although in these animals respiration can be satisfactorily 

 carried on without any pulmonary respiratory movements. The 

 exact way in which this form of diabetes is brought about has not 

 yet been clearly made out. 



A very similar diabetes is seen in carbonic monoxide poisoning; 

 and is one of the results of a sufficient dose of morphia, of amyl- 

 nitrite and of some other drugs. 



468. A diabetes of a permanent character, much more 

 closely resembling the disease as occurring naturally, may be 

 brought about in the following remarkable manner. If in a dog 

 (and the same result may be obtained in many but not all other 

 animals) the whole of the pancreas be removed, sugar makes its 

 appearance in the urine, and the animal soon becomes emaciated, 

 with all the symptoms of ordinary diabetes. Removal of the 

 gland is essential ; mere ligature or blocking of the duct does not 

 produce the effect. And the whole gland must be removed; if 

 only a small portion be left, the symptoms do not appear or are 

 slight and temporary. If the portion left degenerates, as it may in 

 course of time do, after some months for instance, diabetes is at 

 length established. Moreover, it has been found possible to trans- 

 plant a portion of the gland, removing it from its normal surround- 

 ings and grafting it in some other situation. In such a case the 

 whole of the rest of the gland may be removed without causing 

 diabetes; but the symptoms immediately appear if the trans- 

 planted portion be subsequently removed. We may infer that the 

 pancreas, besides secreting pancreatic juice, produces some effect 

 on the blood passing through it, and so on the whole circulating 

 blood, and that this effect has to do with the regulation of the 

 sugar in the blood. So long as even a small portion of the gland 

 is left, adequate effect is produced, and sugar does not accumulate 

 in the blood; but if the whole gland is wanting, then in consequence 

 of the lack of the normal effect, sugar does accumulate in the 

 blood and the condition of diabetes is set up. The salivary glands, 

 in many respects so like the pancreas, have no such action. 



We are not at present in a position to make any dogmatic 

 statement as to what is the exact nature of the effect which the 

 pancreas produces on the blood, whether for instance it manu- 

 factures and discharges into the pancreatic veins some new 

 substance not present in the blood of the pancreatic arteries or 

 whether it destroys or modifies some substance brought to it by 

 the latter, so that this does not appear in the former. We can 

 however at least say that the amylolytic ferment of the pancreatic 

 juice (or its zymogen) has nothing to do with the matter. Nor 

 can we at present say anything very positive as to how the change 

 in the blood thus brought about leads to the accumulation of 

 sugar. It has been supposed on the one hand that the changed 

 blood acting directly on the liver or indirectly through the nervous 

 system or in some other way leads to an over-production of sugar, 



