530 APPENDIX. 



bability, the idea readily suggested itself that all the sugar which 

 was found in the blood originated solely in the liver ; and that that 

 which was formed during digestion was further metamorphosed in 

 the intestinal canal. [This subject is further noticed in pp. 276-291 

 of the present volume.] Moreover we learn from a careful clinical 

 observation , that, at all events in diabetic patients, a saccharine 

 food exhibits an influence on the amount of sugar in the urine. 



There is considerable difficulty in determining the greatest 

 quantity of sugar which can exist in the blood without inducing 

 saccharine urine, and this difficulty may, perhaps, account for the 

 small quantity of sugar found by myself in the blood of a diabetic 

 patient, when compared with that which was found by von Becker 

 in rabbits in which artificial diabetes had been induced by pricking 

 the floor of the fourth ventricle, and in other rabbits, whose 

 blood had been rich in sugar : hitherto von Becker has found 

 that where the blood contains 0'4% of sugar, no portion of it 

 passes unchanged into the urine, although a decided sugar-reaction 

 might be detected in the urine obtained by pressure on the region 

 of the bladder, when its quantity in the blood amounts to 0'6 of 

 this substance. The difference in the nature of the urine in man 

 and these animals may perhaps explain the cause of the high 

 amount of sugar which must be present in the blood of rabbits 

 before it appears in their urine, whilst I could discover so little 

 sugar in the blood of diabetic patients; the alkaline urine of 

 rabbits, as we learn from direct experiments externally to the 

 organism, metamorphoses sugar far more rapidly into acid than 

 human urine ; we must, moreover, bear in mind that diabetic urine 

 is so poor in matters exciting fermentation, that it passes very slowly 

 into a state of fermentation, which may perhaps in some measure 

 explain the difference. I* have, moreover, long since shown that 

 freshly passed urine does not react on vegetable colours in cases of 

 well-marked diabetes, that it is deficient in several of the ordinary 

 extractive matters of normal urine, and that it only gradually 

 acquires an acid reaction on standing exposed to the open air. 



(29) Addition to p. 257, line 20. Genthf has also recently 

 examined the ash of the blood of Limulus Cyclops, which, when 

 fresh, has an azure blue colour, and has found in it a considerable 

 quantity of copper with a little iron. In two analyses of the ash 

 of this blood, he found in 100 parts : 



* De urina diabetica. Diss. inaug. Lips. 1835. 



f Keller u. Tiedemann's Nordam. Monatsschr. Bd. 3, S. 438-441. 



