ORGANS OF THE BODY. 533 



which is maintained by Briicke and denied by others, no definite con- 

 clusions can be come to upon the point. 



The extractive matters of the urine are partly -derived from the products 

 of nmtative processes in the tissues of the body, and partly from the 

 alimentary substances introduced into the latter. Their daily amount 

 varies from 8 to 20 grammes and upwards. Prom Lehmann's researches 

 it would appear that they are most abundant after vegetable food, and 

 appear in small amount under a meat diet. 



We have already referred to the unsatisfactory state of our acquaint- 

 ance with the colouring matters of the urine ( 36). It is a point of 

 interest, however, that indican and indigo-chroinogen have been proved 

 to exist here by Hoppe and Jaffe working on Schenck's and Carter's method 

 ( 36). This explains the fact that blue crystals of indigo (uroglaucin) 

 may be obtained by treating urine with the mineral acids, and that these 

 crystals are found at times in the latter. Indigo- carmine has also been 

 met with here. From the circumstance that indican is not present in 

 the rest of the body according to Hoppe' s investigations, and that it is 

 found in the urine of the lower mammals as well, we may conclude that 

 it is generated by the kidney. 



The mineral matters of the urine are, owing to the nature of the 

 fluid, very variable in their amount. The latter may be set down at from 10 

 to 25 grammes for the twenty-four hours. They consist of chlorides of 

 the alkalies, and indeed almost entirely of compounds of soda, especially 

 of chloride of sodium, which is present in from 1 to 1'5 per cent., 

 amounting in the day, on an average, according to Bischoff, to 14'73 

 grammes, but falling sometimes as low as 8'64, or rising again as high as 

 2i'84 grammes. Chloride of sodium, which is introduced, as is well 

 known, into the system with the food, is a constant constituent of the 

 body. Both the perspiratory glands and kidneys take part in its 

 elimination. There are many points of interest attached to this process. 



If the blood and tissues of the body be saturated with chloride of sodium, 

 all the absorbed salt is again excreted by the organs mentioned. If, on the 

 other hand, the body have previously suffered a deprivation of the salt 

 excretion does not follow upon its ingestion, until the system has recovered 

 its normal percentage of chloride of sodium. If, however, all supply of 

 the latter be cut off, as is the case in starvation or existence on food devoid* 

 of saline ingredients, it still continues to be eliminated, but in much smaller 

 and ever decreasing quantity ( Voit), until, after some days, albumen begins 

 to make its appearance in the urine ( Wundt) a proof of incipient disin- 

 tegration of the blood. 



The amount of chloride of potassium and ammonium in the urine is 

 small on the other hand. 



Urine contains, farther, certain phosphatic salts, and especially acid 

 phosphate of sodium with phosphate of calcium and magnesium. As is 

 well known, the corresponding combination of potash ( 170) is to be 

 found in muscle, while the phosphates of the earths are combined with 

 some of the histogenic substances, and especially albumen. The brain 

 likewise contains phosphorus as one of the ingredients of lecithin. 

 According to the nature of the alimentary matters, phosphoric acid 

 appears in greater or less abundance. It does not, however, fail to be 

 excreted when the system ceases to be supplied with it (Bischoff). 



The amount daily eliminated by tbe kidneys has been estimated by 

 Breed at from 3'8 to 5 '2 grammes. Its rise and fall is to a certain extent 



