MODIFICATIONS OF THE SECRETION OF URINE. 



fluid mass, which probably enters the blood and is the cause 

 of death. 



The other physiological conditions that affect the urinary 

 excretion influence the composition of the urine and the 

 quantity of excrementitious matters separated by the kid- 

 neys. These will be more appropriately considered under 

 the head of nutrition and disassimilation. It is sufficient to 

 remark, in this connection, that during digestion, when the 

 composition of the blood is modified by the absorption of 

 nutritive matters, the quantity of urine is usually increased. 

 This is particularly marked when a large amount of liquid 

 is taken. There are certain modifications due to the con- 

 dition of the blood in disease, but these do not belong to 

 the subject of physiology. The same may be said of the 

 elimination of foreign matters introduced into the circula- 

 tion, and the excretion of sugar by the kidneys when this 

 substance is produced in the system in excess. 



The prompt separation of certain matters from the blood 

 by the kidneys has been illustrated by experiments upon ani- 

 mals, and by observations on the human subject in cases of 

 extroversion of the bladder, in which the urine could be im- 

 mediately collected as it flowed from the ureters. In a case 

 of this kind observed by Erichsen, the ferrocyanide of potas- 

 sium taken into the stomach after a fast of eleven hours 

 appeared in the urine in one minute. In this case, numer- 

 ous experiments were made with other articles, which it is 

 unnecessary to follow out in detail. 1 



As the excrementitious principles eliminated by the kid- 

 neys are being constantly produced in the tissues by the 

 process of disassimilation, the formation of urine is constant ; 

 presenting, in this regard, a marked contrast with the inter- 

 mittent flow of most of the secretions proper, as distinguished 



1 ERICHSEN, Observations and Experiments on the Rapidity of the Passage of 

 some Foreign Substances through the Kidnies, and on some Points connected with 

 the Excretion of the Urine. London Medical Gazette, London, June 27, 1845, 

 New Series, vol. ii., p. 363. 



