424 OP SECRETION. 



ter, whether introduced from without, or generated within the system, 

 are drawn off by the same channel. Thus the saline compounds, taken 

 up by the absorbent process ( 493), are for the most part set free 

 through these organs ; especially when their properties are such, as to 

 excite the action of the kidneys in a peculiar degree. Thus, Prussiate 

 of Potash has been detected in the urine, within one minute after it 

 has been introduced into the stomach. It has been sometimes noticed 

 that Iodide of Potassium, when administered as a medicine, is retained 

 within the body for some days, producing extensive cutaneous erup- 

 tions, or some other unusual consequence ; and that it then suddenly 

 begins to pass off by the kidneys, and is excreted in very large quan- 

 tities. Further, it has been shown by Dr. Letheby, that poisonous 

 substances (such as arsenious acid), introduced into the system in 

 small but frequently-repeated doses, may be carried out of the body 

 with such rapidity as to be prevented from exerting their injurious 

 effects, provided that diuretics be administered at the same time. The 

 effect of the inhalation of the vapour of turpentine, even in a very 

 diluted state, in speedily imparting to the urine the odour of violets, is 

 an evidence that not merely the actual substances imbibed, but new and 

 peculiar compounds to which they give rise, are thus eliminated by the 

 Kidneys. 



756. The most singular variations in the excretory function of the 

 Kidneys are seen, however, when the Urine is charged with substances 

 which are not only foreign to it, but are altogether foreign to the 

 healthy body. The most remarkable instance of this is seen in the 

 disease termed Diabetes, in which a large quantity of Sugar is formed, 

 either directly from the food, or by the disintegration of the solid 

 tissues ; and in which this compound is eliminated by the Kidneys, 

 imparting to the urine a saccharine taste. And another example of 

 the same general fact is seen in the " oxalic diathesis," in which an 

 unusual arrangement of the elements that usually form urea or uric 

 acid, gives rise to a new and peculiar compound, oxalate of ammonia ; 

 this being drawn off by the kidneys, and being decomposed by the 

 calcareous matter present in the urine, gives rise to a deposit of oxalate 

 of lime. In the treatment of such diseases, our attention must be given, 

 not so much to the secreting organ, as to the condition of the system at 

 large, of which the character of the secreted product is the indication 

 or exponent. 



757. To what has already been stated in regard to the exhalant 

 functions of the Lungs and Skin, it may be added that many states of 

 disease are marked by an unusual odour emitted from the body ; and 

 there can be little doubt that the peculiar odorous matter is pre-formed 

 in the blood, as we know that the ordinary scent of any species 

 (whether Man, Dog, Horse, Goat, &c.) may be set free from the blood 

 of that species, by the addition of sulphuric acid. The existence of 

 such odours, therefore, is not to be attributed to disordered function in 

 the excreting organs ; but to the formation of morbid products in the 

 interior of the body, which these organs do their best to remove. The 

 foetid breath, which frequently accompanies an attack of indigestion, is 

 another instance of the power of the lungs to eliminate, not merely 



