OF TUB FUNCTIONS OF THE KIDNIES 



ted by the mucous membrane of the intestines themselves. While we would not al- 

 together deny a snare in its production to the former, we contend for the latter. We 

 believe that the mucous membrane of the digestive canal may both secrete gaseous sub- 

 stances and absorb them ; and we found our belief upon the following circumstances: 

 1st, We have proofs derived from experiment and observation that gaseous substances 

 are absorbed and given oft' from the mucous membrane of the respiratory apparatus. 

 2d, Pathological facts intimately connected with the functions and properties of this 

 membrane in different parts of the body, support the position. We have, however, no 

 doubt that the changes ^hich the alimentary substances undergo in the stomach occasi- 

 onally gives rise to gaseous products; and we believe that a similar result follows the 

 remoVa of the excrernentitial matters in the colon and rectum. As to the chemical cha- 

 racters of the gaseous substances found in different parts of the intestinal tube, see 

 Chapter II, 



Of the Functions of the Kidneys, 



Note P. 



The latest, and, we think, the most correct examination of the intimate structure of 

 the kidnies was given in the text. We now add the ktest experiments which have been 

 made, in order to ascertain the extent of their functions. Messrs. Dumas and Prevost, of 

 Geneva, and afterwards Mr. Segales, of Paris, found on examining the blood of living 

 animals, whose kidnies had been extirpated, that it contained urea*, the quantity of 

 which was increased in proportion to the duration of life after the operation ; whilst 

 this substance could not be detected in the blood of those animals in which the urinary 

 secretion was uninterrupted. The last mentioned physiologist, moreover, having in- 

 jected an aqueous solution of urea into the veins of an animal, observed the secretion of 

 urine rapidly increased by it, this substance so quickly eliminated in the process that, 

 after twenty -four hours, it could not be detected in the blood. It seems, therefore, 

 not improbable that the debris of the textures, being carried into the circulation, is con- 

 verted by the influence of the organs and vessels through which it flows into the sub- 

 stance called urea, and that the function of the kidnies is to eliminate it, with other 

 materials which would be hurtful to the system. These experiments, show that the urea 

 is not formed in the kidnies by their appropriate functions, as was believed by some phy- 

 siologist, but that it, and, probably other materials which are removed from the blood 

 by these organs, are deriverd from other sources. 



The following facts more closely relate to pathology, than to physiology. 



In inflammatory fever the urine is red or deep coloured, or even a deep brown, and 

 perfectly transparent until the disease tends to a termimation ; it then deposits the la- 

 terititious sediment, which is of a reddish colour, and consists of animal matter, phos- 

 phate of lime, lithic acid, and sometimes lithate of ammonia, According to i)r. Prout 

 lithateof soda, and phosphates of ammonia and soda, are also present. In intermittents 

 the appearance of the urine varies according to the stage of the desease ; but when a 

 paroxysm of ague is over, what is then voided deposits a peculiarly red powder, which 

 has been examined by Dr. Prout, and found to be a distinct acid, which he named ros- 

 acic acid, from its colour. In typhus fevers, the urine is loaded with gelatin and urea. 

 It deposits in gouty disorders, as it cools, a large quantity of lithic acid, in the form of 

 red crystals. The urine in hysteria is of a very pale colour ; it contains abundance of 

 saline ingredients, but is very deficient in urea and animal matter. In jaundice it is 

 usually of a brown colour, arising from an admixture of bile. In various other disor- 

 ders, especially those affecting the secreting function of the liver, more particularly 

 \rhen that function is imperfectly performed, the urine very generally presents a brown 

 and muddy appearance, owing to the kidnies having assumed an action in some degree 

 vicarious of that of the liver, and thus removed much of the carbonaceous and effete 

 materials from the blood usually eliminated by that viscus. A similar appearance of the 

 tirine is often met with in those fevers wherein the functions of the liver are much em- 

 barrassed, especially in those fevers called bilious, and in those which are met with in 

 warm climates- In ascites this fluid frequently assumes a yellowish green colour, and 

 is extremely viscid. It deposits a copious sediment of rosacic acid mixed with lithic 

 acid, phosphate of lime, and animal matter ; and is often loaded with albumen to such 



* Five PI. in res of blood contain one scruple cf urea, 



