- Bacteria as Agents in the Oxidation of Amorphous Carbon. 239 
whether the state of the gut favourable to the formation of coprosterol 
persisted when the next diet (oatmeal) was tried, as, owing to an accident, the 
whole of the ethereal extract was lost. In the subsequent experiment with 
horseflesh, the gut had recovered its normal condition. 
Whether any of the cholesterol of the food is actually absorbed along with 
that of the bile in the intestine, these experiments do not show, but others 
are in progress, which we hope will throw light on this point, and this we 
hope to make the subject of a communication in the near future. 
The expenses in connection with this work were defrayed by means of a 
grant made by the Government Grant Committee of the Royal Society, for 
which we take this opportunity of expressing our thanks. 
Bacteria as Agents in the Oxidation of Amorphous Carbon. 
By M. C. Portrer, M.A., F.L.S., Professor of Botany, Armstrong College, in 
the University of Durham. 
(Communicated by J. B. Farmer, F.R.S. Received March 13, 1907,—Received in 
revised form, with additional matter, January 18,—Read March 12, 1908.) 
The problem which presented itself to my mind in commencing the 
following investigation was primarily one connected with agriculture. When 
considering the application of such insoluble substances as charcoal, cinders, 
soot, etc., to the land, an explanation was sought of their ultimate fate in the 
soil. What becomes of the carbon? Is it oxidised into COs, and if so by 
what agency ? 
Little is known at present as to the means whereby amorphous carbon is 
rendered available for plant life, except through its union with oxygen in the 
process of combustion, and further investigation upon this point offered an 
important field of enquiry. It is well established that carbon readily 
absorbs oxygen, and, in the case of coal, that carbonic acid is given off, but the 
cause of the latter phenomenon is still obscure, and in the theories advanced 
to account for it no consideration is ever given to the possible action of 
micro-organisms. 
My investigations have shown that under the action of certain bacteria a 
slow oxidation of amorphous carbon takes place, CQ2 is slowly evolved, and 
the carbon can thus be at once utilised for the nutrition of green plants. 
