270 
DR. MARCET ON THE IMMEDIATE PRINCIPLES OF 
found to have the following 1 properties. When obtained directly from its solution 
in ether, the crystals consist of large, rectangular plates, which, when viewed with 
the naked eye, floating in the mother-liquor, have the appearance of light shining 
crystals with a pearly or silky lustre. When collected upon a filter, they rapidly 
lose their shining nature, which is not the case with cholesterine. Like chole- 
sterine, however, they are insoluble, or very sparingly soluble in cold alcohol, but 
dissolve readily in hot alcohol, from whence the substance again crystallizes on 
cooling. The crystals thus obtained still possess the same silky shining lustre as in 
the previous case, but when subjected to the microscope are found to have lost their 
rectangular shape, and to have assumed various irregular forms, resembling flies or 
butterflies with extended wings ; they still polarize light very readily. If a few of 
them be dissolved in a comparatively large amount of alcohol, the substance assumes, 
on crystallizing, remarkably curious and beautiful forms. Its alcoholic solution has 
a slightly alkaline reaction ; its fusing-point is very high, above 100° Centigrade. 
The substance just described cannot possibly be mistaken for excretine, and I 
should be inclined to consider it as a new immediate principle, unless further inves- 
tigation should show its complete analogy with cholesterine. It must at all events 
act an important part in the functions of the spleen, from its having been ascertained 
to exist as one of the immediate principles of this organ in every case where the 
spleen was subjected to examination. 
Among the intestinal secretions, I have only examined bile (oxen’s bile), which 
yielded no excretine, but only cholesterine, from which circumstance it may be 
inferred that the method employed for obtaining excretine may also be made use of 
with advantage to extract cholesterine from its solutions. Indeed, bile contains so 
small a quantity of cholesterine, that this principle cannot easily be obtained by the 
usual method, except by operating upon a very large quantity of fluid. 
Excretine was not detected in healthy human urine treated by the same method ; 
the lime precipitate, carefully washed with water in order to separate every trace 
of urea, yielded no perceptible extract to ether. 
Blood, human bile, the cerebral and osseous tissue, pancreatic juice, saliva, gastric 
juice, &c., have not yet been examined in order to ascertain whether they contain 
excretine. If further experiment shows that this substance can be obtained in no 
other case than in that of the intestinal evacuations, its formation must evidently 
result from a metamorphosis or decomposition owing to the action of the solid 
ingesta upon the intestinal secretions. 
From the singular circumstance that excretine contains sulphur, it is not unlikely 
that the formation of this immediate principle may depend upon a decomposition of 
taurine, the only sulphuretted compound which, with the exception perhaps of a 
very small quantity of cystine, can be obtained from the intestinal secretions. 
Another and very important conclusion resulting from the presence of sulphur in 
excretine, is, that sulphur is thus eliminated from the body without undergoing 
