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DR. MARCET ON THE IMMEDIATE PRINCIPLES OF 
transparent globules, resembling exactly those obtained by the same process from 
the castings of the Horse. No crystals were deposited by the ethereal solution. 
My investigations upon the chemical constituents of the castings of animals show, 
therefore, — 
1st. That they contain no excretine, thus differing very materially from human 
evacuations. 
2nd. That the castings of carnivorous mammalia contain,— (1) a peculiar crystal- 
line organic substance obtained by the same process as excretine ; (2) butyric acid , 
existing probably in the form of a salt, as one of their constituents. 
3rd. That the castings of the Crocodile yield cholesierine. 
4th, That the castings of herbivorous animals contain no excretine and no butyric 
acid, and do not yield the crystalline substance obtained from those of carnivorous 
animals, except perhaps in the case of the Monkey. 
