GENERAL CONSIDERATIONS. 109 



held in solution in water. The character of these principles 

 depends upon the constitution of the blood and the general 

 condition of nutrition, and not upon any formative action in 

 the glands. The principles themselves represent the ulti- 

 mate physiological changes of certain constituent parts of 

 the living organism, and are in such a condition that they 

 are of no further use in the economy and are simply dis- 

 charged from the body. Certain inorganic matters are 

 found in the excrementitious fluids, are discharged with 

 the products of excretion, and are thus associated with the 

 organic principles of the economy in their physiological de- 

 struction, as well as in their deposition in the tissues. Co- 

 agulable organic matters, such as albumen or fibrin, never 

 exist in the excrementitious fluids under normal conditions ; 

 except as the products of other glands may become acciden- 

 tally or constantly mixed with the excrementitious fluids 

 proper. The same remark applies to the non-nitrogenized 

 matters (sugars and fats), which, whether formed in the 

 organism or taken as food, are consumed as such in the pro- 

 cess of nutrition. The production of the excretions is con- 

 stant, being subject only to certain modifications in activity, 

 dependent upon varying conditions of the system. All of 

 the elements of excretion preexist in the blood, either in the 

 precise condition in which they are discharged, or in some 

 slightly modified form. 



Under the head of excretion, it is proposed to consider 

 the general properties and composition of the different ex- 

 crementitious fluids ; but the relations of the excrementitious 

 matters themselves to the tissues will be more fully treated 

 of in connection with nutrition. 



The urine is a purely excrementitious fluid. The perspi- 

 ration and the secretion of the axillary glands are excre- 

 mentitious fluids, but contain a certain amount of the secre- 

 tion of the sebaceous glands. Certain excrementitious 

 matters are found in the bile, but at the same time, this 

 fluid contains principles manufactured in the liver, and has 



