132 THE SECRETIONS CONTAIN 



formed and developed from the blood or the con- 

 stituents of the blood, that the existing organs at 

 every moment of life are transformed into new com- 

 pounds under the influence of the oxygen introduced 

 in the blood, then the animal secretions must of 

 necessity contain the products of the metamorphosis 

 of the tissues. 



22. If it be further true, that the urine con- 

 tains those products of metamorphosis which contain 

 the most nitrogen, and the bile those which are 

 richest in carbon, from all the tissues which in the 

 vital process have been transformed into unorganised 

 compounds, it is clear that the elements of the bile 

 and of the urine, added together, must be equal, in 

 the relative proportion of these elements to the com- 

 position of the blood. 



23. The organs are formed from the blood, and 

 contain the elements of the blood ; they become 

 transformed into new compounds, with the addition 

 only of oxygen and of water. Hence the relative 

 proportion of carbon and nitrogen must be the same 

 as in the blood. 



If then we subtract from the composition of blood 

 the elements of the urine, then the remainder, de- 

 ducting the oxygen and water which have been 

 added, must give the composition of the bile. 



Or if from the elements of the blood, we subtract 

 the elements of the bile, the remainder must give 

 the composition of urate of ammonia, or of urea 

 and carbonic acid. 



