GENERAL DISORDERS OF NUTRITION. 



The most specious of the hypotheses, as to the pathogeny of 

 insipid diabetes, is that which ascribes the polyuria to derangement 

 of innervation of the blood-vessels of the kidney. If the afferent 

 vessels of the Malpighian capsules were to become dilated, in conse- 

 quence of paralysis of their walls, the pressure within the glome- 

 rali would increase, and with it the rate of filtration of the urine 

 would augment, thus giving rise to polyuria. This primary symptom 

 would be accompanied secondarily by polydipsia. When large quan- 

 tities of water are withdrawn from the blood, as a consequence of pro- 

 fuse urination, then (just as also occurs after profuse sweating, or 

 intense liquid diarrhoea) the fluids from the interstices of the tissues 

 are greedily absorbed by the now concentrated blood, thus giving rise 

 to an increased need for liquid, and to a sense of severe thirst. Al- 

 though I regard this as probably a true explanation, and although it 

 acquires further support from the discovery of Bernard, that polyuria 

 may be induced in animals by wounding their medulla oblongata at a 

 point somewhat farther up than that at which the so-called " diabetes 

 puncture " is performed, yet I am by no means inclined to regard it 

 as absolutely correct. 



With regard to the somewhat obscure etiology of diabetes insipi- 

 dus, we must confine ourselves to the announcement of the following 

 facts : The disease is more common in males than in females, and in 

 youth than during middle age. I cannot confirm the assertion that 

 old age is exempt from it, as I have seen a case in a patient fifty years 

 old. Its exciting causes have so often been referred to mental affec- 

 tions, to the drinking of cold beverages while the body was over- 

 heated, to cold, to over-exertion, to abuse of spirituous liquors, and 

 other agencies, of a nature so- various, and of such common occurrence, 

 that the dependence of the malady upon their influence must be 

 regarded as questionable. 



It is different with the observations of cases where diabetes 

 insipidus has occurred after injuries of the skull, and in the course 

 of acute and chronic diseases of the brain. These cases, in con- 

 nection with the above-mentioned experiments of Bernard, are 

 peculiarly interesting. 



ANATOMICAL APPEARANCES. The results of the small number of 

 autopsies held upon persons who have suffered from diabetes insi- 

 pidus agree so imperfectly, that nothing positive can be affirmed 

 regarding the anatomical lesions from which the malady originates. 

 Thus, in a case described by Neuffer, the kidneys, contrary to all expec- 

 tation, were found small and atrophied, while in another, mentioned by 

 Lebert, they were enlarged and hypertrophied. 



SYMPTOMS AND COURSE. The amount of urine discharged by a 



