RETENTION OF CHLORIDES IN THE BODY 709 



secretion of urine. For instance, the fact that sugar does not 

 appear in more than traces in the urine unless there is an excess 

 of dextrose in the blood. Hyperglycaemia is present in all forms 

 of glycosuria except phloridzin diabetes, and in this condition it is 

 supposed by Loewi, Pavy, and Lusk that a sugar colloid com- 

 pound is broken up in the kidney, and the dextrose so liberated 

 is excreted. Indeed, the facts connected with phloridzin diabetes 

 are capable at present of no other explanation. The theory can 

 explain also why a diuretic leads to an increased excretion of sugar 

 in all forms of glycosuria excepting phloridzin diabetes, and why in 

 this last condition, in dogs at any rate, the diuresis produced by 

 phloridzin is not accompanied by an increased excretion of 

 chlorides. It readily explains why in some experiments and in 

 individual animals no urine is excreted unless there is added to 

 the blood in excess some substance capable of passing into the 

 urine. For instance, Munk found that when the blood of a fasting 

 dog was circulated through an excised kidney, no secretion of 

 urine took place unless a chloride, sugar, urea, &c., was added. 

 Nussbaum found that no urine was secreted by a frog after ligature 

 of the renal arteries unless urea was injected. Magnus's experi- 

 ment of transfusing whole blood has been referred to ; he found 

 no diuresis unless the composition of the transfused blood was 

 abnormal. Spiro in the same way found that the injection into 

 fasting animals of solutions of gum or gelatine caused no diuresis, 

 even with the aid of caffein, although the quantity of fluid in 

 circulation had been increased by 80 per cent. ; if, on the other 

 hand, the animals had been fed and well watered beforehand, then 

 diuresis resulted. The different degrees of diuresis produced by 

 equimolecular solutions of different salts could be explained on 

 the supposition that sodium chloride enters more easily into a 

 non-filterable combination with colloid than sodium sulphate, and 

 therefore has a superior diuretic action. Most of these observa- 

 tions are, as we have seen, capable of other explanations. How- 

 ever simple Forster's theory may be, it lacks the necessary demon- 

 stration that compounds of crystalloids with colloids really do 

 exist in the blood or elsewhere. For instance, it has been found 

 that the freezing-point of a solution of sodium chloride is not 

 altered by the addition of albumose or egg albumin to it. Further, 

 Martin, Starling, and Waymouth Reid have found that by filtering 

 serum through a gelatine membrane the bulk of the crystalloids 



