398 DIGESTION. 



of the normal faeces ; and the stercorine we have found to be 

 one of the most distinct and important of the excrementitious 

 principles in the body. 1 The relations of excretine to the 

 process of destructive assimilation of the tissues have not 

 been so clearly indicated. 



Excretine and Excretoleic Acid. Excretine was obtained 

 by Marcet from the healthy human faeces in the following 

 way : The faeces were first treated with boiling alcohol until 

 nothing more could ' be extracted. This alcoholic solution 

 was acid and deposited a sediment on cooling. Milk of lime 

 was then added to the solution, producing a yellowish-brown 

 precipitate, and leaving the fluid of a clear straw-color. The 

 precipitate was then collected on a filter, dried, afterward agi- 

 tated with ether and filtered, forming a clear yellow solution. 

 In from one to three days, beautiful long silky crystals of 

 excretine were formed, generally collected into tufts adhe- 

 ring to the sides of the vessel. Examined by the microscope, 

 these were found to consist of acicular four-sided prisms of 

 variable size. This substance is insoluble in water, slightly 

 soluble in cold alcohol, but very soluble in ether and hot 

 alcohol. Its alcoholic solutions are faintly, though distinctly, 

 alkaline. Its fusing point is from 203 to 205 Fahr. It 

 may be boiled with potash for hours without undergoing 

 saponification.* In a second paper by Marcet, published in 

 1857, the composition of excretine is given as C^IPO'S 1 . It 

 was also found that its crystallization was facilitated by cold.* 

 Apparently, the quantity of excretine contained in the faeces 



J In 1833, Boudet described a new substance as existing in the serum of the 

 blood, which he called Seroline. (Nouvclles Recherches sur la Composition du 

 Serum du Sang. Annales de Chimie et de Physique, Paris, 1833, tome Hi., p. 

 337.) This is the substance which we discovered in the faeces, and have de- 

 scribed under the name of Stercorine. 



2 MAECET, Philosophical Transactions^ 1854, p. 265 et seq. 



8 Excretine has not yet been made to enter into any definite combinations, 

 and its formula is calculated on the assumption that one equivalent of excretine 

 contains one equivalent of sulphur. 



