EXPERIMENTAL DIABETES 363 



diabetes in which hyperglycaemia exists (pancreatic diabetes, &c.), 

 whereas in phloridzin diabetes, although diuresis is produced, no 

 increased amount of sugar is excreted. The increased volume 

 of blood which perfuses the kidney blood-vessels, as a result of 

 the action of these diuretics, allows more sugar to pass the kidney 

 filter when hyperglycsemia exists, but it does not stimulate the 

 kidney cells to increased production of sugar when they are 

 poisoned by phloridzin. 



2. Injury to the kidney, whether mechanical or produced by 

 drugs or by disease, markedly diminishes its power of secreting a 

 saccharine urine when it is subjected to the action of phloridzin. 



3. Histological examination of the uriniferous tubules after 

 prolonged phloridzin administration reveals necrotic changes in 

 the cells. 



The mother substance of the sugar is undoubtedly the serum 

 proteid. It will be remembered that when the animal is liberally 

 fed with carbohydrate much sugar is excreted in the urine without 

 there being any rise in the nitrogen excretion, but that when 

 starved of carbohydrate the amount of sugar falls and that of 

 nitrogen rises. This must mean that in the well-fed animal, the 

 sugar can be split off from the serum proteid without there being 

 any disruption of the proteid molecule, and hence no rise in the 

 excretion of nitrogen. Chemical evidence that this is possible 

 we have given above (p. 319). This sugar is loosely combined 

 with the proteid in the same way that oxygen is combined with 

 hemoglobin in oxy-hsemoglobin. 



Further evidence that such a sugar-carrying function belongs 

 to the blood proteid has recently been furnished by Embden and 

 Blumenthal ( 2 ). The former worker has found that if a glycogen 

 and jecorin 1 -free liver is perfused with blood, sugar accumulates 

 in it. 



Blumenthal applied Bial's reaction for aldo-hexoses (see p. 318) 

 to serum globulin prepared from the blood of animals rendered 

 diabetic by phloridzin, and obtained a very faint reaction ; whereas 

 with serum globulin prepared from a well-fed normal animal a 

 very distinct reaction was noted. 



It is not supposed that all the dextrose in the blood is thus 



1 Jecorin is a compound of lecithin and dextrose, and has been described by 

 Henriques and Bing as the substance in the blood in chemical combination with 

 which dextrose is carried. 



