708 RETENTION OF CHLORIDES IN THE BODY 



pressure more than counteracting the local constriction in the 

 kidney. This explanation seems to be favoured by an observa- 

 tion of Marshall, that a combination of digitalin with a vaso- 

 dilator, such as nitro-glycerine, increased the diuretic effect of 

 digitalin. Unfortunately he did not record the kidney volume, 

 which robs the experiments of much value in this connection. 

 On the other hand, the investigation of the action of strophanthin 

 is strong evidence against this explanation of the action of 

 digitalin. For an injection of strophanthin causes a marked rise 

 in the arterial blood pressure, due to its action on the heart alone 

 and without any peripheral vaso-constriction, the kidney volume 

 is correspondingly increased, and yet the flow of urine is unaltered. 



We again reach the same conclusion, that the vascular changes 

 are no more a complete explanation of the action of these than 

 of the saline diuretics ; but we are unable to decide in what other 

 way they act. 



The Retention of Chlorides in the Body. It is a well-known 

 fact that in pneumonia and other fevers the percentage and total 

 excretion of chlorides in the urine may be greatly reduced. The 

 cause of this reduction is largely due to deficiency of chloride in 

 the food, as Hatcher and Sollmann have shown. The chloride 

 content of the blood, however, is not reduced, and, further, large 

 quantities of chloride given by the mouth may be retained in 

 the body. The mechanism of this salt retention can be explained 

 on either Lud wig's or Heidenhain's view. On either view we 

 should have to suppose that, when the body cannot afford to 

 part with chloride, this fact is communicated to the kidney cells, 

 so that either chlorides are more fully absorbed from the glomerular 

 filtrate or the cells of Bowman's capsule do not secrete them. In 

 both cases the alteration would be due to the vital activity of 

 cells. 



Forster has given a purely physical explanation of this pheno- 

 menon. He believes that crystalloids in the blood may exist in 

 two states : a small part free and able to pass through the glomer- 

 ular epithelium, and a larger part in combination with colloid and 

 unable to be passed through the glomerulus. Consequently the 

 glomerular filtrate would contain, not the entire ash, but only the 

 salts of the plasma which were free, that is, beyond the combining 

 power of the colloid present. This theory could be made to 

 explain many of the ascertained facts in connection with the 



