212 Messrs. Dorée and Gardner. Origin and  [Dec. 20, 
with which it was combined, the acidity attained in this way being equivalent 
to that of the soil water on the acid plots. | 
The authors attribute the continuance of the nitrification in these soils 
to the irregular distribution of the materials composing them; though acid 
as a whole, they still contain some calcium carbonate, each of the particles 
of which forms a centre for the nitrification process. The decline in fertility 
of the acid plots may be attributed to the repression of the normal bacterial 
activities of the soil and the encouragement of the growth of moulds. 
The Origin and Destiny of Cholesterol in the Animal Organism. 
Part IL—On the so-called Hippocoprosterol. 
By CuHaries Dorks, Lindley Student of the University of London, and 
J. A. GARDNER, Lecturer in Physiological Chemistry, University of 
London. | 
(Communicated by Dr. A. D. Waller, F.R.S. Received December 20, 1907,— 
Read January 23, 1908.) 
(From the Physiological Laboratory of the University of London.) 
Introductory. 
Since the discovery of cholesterol by Conradi in 1775, and its analysis by 
Chevreul in 1815, it has been found to be very widely distributed in the 
animal and in isomeric forms in the vegetable kingdom. It is found 
in small quantities in all protoplasmic structures, in blood, bile, sebum, and 
similar oily excretions of the skin, and is an especially abundant constituent 
of the white substance of brain and of the medullary sheath of nerve. But, 
although a considerable amount of work has been done, we have little or no 
definite knowledge of its physiological functions, and it is only in very recent 
times that a small glimmering of light has been thrown on its chemical 
constitution. 
In 1862, Austin Flint* published a series of experiments by which he 
attempted to show that cholesterol is always more abundant in the blood 
coming from the brain than in the blood of the general arterial system, or 
in the venous blood from other parts; that its quantity is hardly appreciable 
in venous blood from the paralysed side in hemiplegia, and that it is 
* “Kxperimental Researches into a new Excretory Function of the Liver,” ‘ American 
Journal of Medical Sciences,’ Philadelphia, 1862, new series, vol. 44, and “ Recherches 
Expérimentales sur une Nouvelle Fonction du Foie,” Paris, 1868. 
