iQii] William J. Gies 299 



two parts: first, the effect of the water injected, second, the effect of 

 the Salt. Other things being equal, we may expect the water to behave, 

 so far as diuresis is concerned, just as this behaves when water only 

 is injected. The salt injected has an effect upon the kidney and also 

 upon the colloids of the body generally, including those of the blood 

 and lymph. As the chief salt of the body fiuids is sodium chloride, we 

 are not surprised to find that a sodium chloride Solution isosmotic with 

 the blood, when injected intravenously, acts about as the injection of 

 an equal amount of water (the minor effects of pure water as a plas- 

 molyzing agent on the blood, etc., not being taken into consideration). 

 If, however, a sodium chloride Solution having an osmotic concentra- 

 tion above that of the blood is used, an increased secretion of urine is 

 obtained. This is because the salt acts not only directly upon the col- 

 loids of the blood and makes them liberate some of their water, but 

 diffuses into the tissues of the body and makes the colloids here also 

 give up a part of their water. This water is then " free," and can be 

 secreted as urine. The salt also acts upon the colloids of the kidney, 

 making the cells of this organ shrink. This shrinkage of the kidney 

 cells necessarily means a change in the physical Constitution of the 

 previously described colloidal membrane that separates the urine from 

 the blood. We can say that this change makes for an " increased per- 

 meability " of the membrane, but the real physics that underlies this 

 designation cannot yet be satisfactorily goneinto. The higher the con- 

 centration of the injected salt the more water must the body tissues 

 yield up for diuresis (and the more "permeable," perhaps, also may 

 we consider the kidney membrane to become to water). (Page 196.) 



Frey finds that when water is given a rabbit by mouth or rectum, or 

 is injected intraperitoneally, or into the small in testine, an increased 

 amount of urine is secreted by the kidneys. I would say that this is 

 because the tissues of the rabbit are saturated with water and so none 

 of it is retained. If in place of water a sodium chloride Solution is 

 injected, the same or even a greater diuresis is obtained. This diuresis 

 is the greater the higher the concentration of the salt Solution injected 

 (the amount of fluid injected being the same), just as in the experi- 

 ments of my own already described. (Page 198.) 



The diuresis following the introduction of water does not occur if 

 any anesthetic is administered (morphine, chloral, ether, urethane). 

 This is evidently because the anesthetics all produce a State of lack of 

 oxygen, so that the tissues have an increased affinity for water and so 

 do not secrete that which has been absorbed from the alimentary tract 



