Royal Society. 65 



allied genera of Orchideae, and indicates some of the more important 

 morphological changes to which that organ is subjected, in con- 

 nexion with the development of various appendages to the column 

 and pollen in the same natural family. 



" On the Immediate Principles of the Excrements of Man and 

 Animals in the Healthy Condition," by William Marcet, M.D. 



The author describes a new method of extracting the immediate 

 chemical constituents of the excrements of Man and animals, and 

 gives an account of the substances obtained by its employment. 



Healthy human faeces are boiled to exhaustion in alcohol. The 

 residue is insoluble in aether, and yields to boiling water nothing but 

 ammoniaco-magnesian phosphate. The strained alcoholic solution 

 deposits, on standing, a sediment, from which it is decanted and then 

 mixed with milk of lime. The subsiding lime is of a yellow-brown 

 colour ; it is dried on filtering-paper and treated with aether, cold or 

 hot, and the solution thus obtained yields, on spontaneous evapora- 

 tion, beautiful silky crystals, which are purified by solution in a 

 mixture of alcohol and aether, repeated filtration through animal 

 charcoal and recrystallization ; they then appear in circular groups, 

 have the form of acicular four-sided prisms, and polarize light very 

 readily. This crystalline body the author proposes to call Excretine. 

 It is very soluble in aether, cold or hot, but sparingly soluble in cold 

 alcohol; its solution has a decided though weak alkaline reaction. 

 It is insoluble in hot or cold water, and is not decomposed by dilute 

 mineral acids. It fuses between 95° and 96° C, and at a higher 

 temperature burns away without inorganic residue. When boiled 

 with solution of potash it does not dissolve. As to its qualitative 

 constitution, it is found to contain nitrogen and sulphur, though in 

 small proportions ; the products of its decomposition have not yet 

 been investigated. 



The author has in several cases observed the excretine to crystal- 

 lize directly in the alcoholic solution of faeces before the addition of 

 lime, and has scarcely any doubt that it exists for the most part in 

 a free state in the excrements, and constitutes one of their imme- 

 diate principles. As to its source, he observes that it appeared in 

 excess when a considerable quantity of beef had been taken, and in 

 less than the usual quantity in a case of diarrhoea attended with 

 loss of appetite ; but none' could be directly obtained from beef on 

 subjecting it to the same process of extraction as faeces. Neither 

 could it be found in ox-bile, the urine, or the substance of the spleen. 

 From the difficulty of obtaining the contents of the human small in- 

 testine in a healthy state, its presence or absence in that part of the 

 alimentary canal has not yet been satisfactorily determined. 



The lime precipitate, after having been thus thoroughly deprived 

 of the excretine by Dother, is next treated with hydrochloric acid, 

 and water or alcohol, by which means margaric acid is extracted 

 from it. The author is uncertain whether the margaric acid of the 

 faeces is free or combined with excretine, but he is disposed to con- 

 clude that the neutral fats are decomposed in the intestinal canal 

 and their acid set free. Not having been able to detect stearic acid 

 Phil. May. S. 4. Vol. *J. No. 5G. Jan. 1H55. F 



