April, 1910.] 
The Bacterial Flora. 
J 43 
At the end of the experiment a chemical examination of the 
peptone culture solutions, made by Dr. Lyman, indicated the 
presence of indol, ammonia and various non-volatile products in 
various proportions. A marked difference was noted in the 
ability of the different species of bacteria to produce indol and 
ammonia. The highest quantity of ammonia was produced by 
B. 13; the least amount was recorded for B. 1 cc. — the culture 
solution, it will be remembered, which consisted of a mixture of 
the bacteria found in one cubic centimeter of fresh bog water. 
None of these products were found in the control (sterilized bog 
water and peat). It is also to be noted that neither the organic 
acids nor the ammonia underwent a further change and that the 
absence of atmorpheric air is not a limiting essential condition 
for the growth of the bacterial organisms. Interesting is the 
fact that the organisms belong for the most part to the aerobs. 
The mixture culture solution (B. 1 cc.) in which the percentage 
decrease in transpiration was as low as 90%, seems to show that 
it is the function of some of the bacterial organisms to do the 
initial work of rendering soluble the protein compounds in the 
soil. The process of denitrification is carried on up to a point 
where further decomposition is continued by other organisms. 
Judging from the differences in the transpiration values of the 
various cultures, a whole series of bacteria seems therefore to be 
involved to whom are due the residual products, the algebraic 
sum of which in part constitutes the toxicity of the habitat 
encountered on Cranberry Island, the formation of methane gas, 
and the reactions which form the basis of the process of 
humification. 
Thus far the isolation of bacteria involved in the decompo- 
sition of carbohydrates has not been successful. Certain micro- 
organisms have been found to possess the ability to dissolve 
cellulose (filter paper) in the presence of air. To what extent 
these forms and the anaerobs play a role in the relation of 
deleterious products in the soil and cultivation of crops is now 
under investigation. 
It is not proposed to dwell upon the general aspect of this 
problem in this place. In a previous paper (Botanical Gazette 
47: 389-405, 1909) the writer has reported that the poisonous 
matter injurious to plant growth is present in the agricultural 
soils used as filters for bog water. The retardation seen in the 
contaminated soils lacked the corresponding control average in 
dry weight of plants to an amount of 18 per cent, 3 per cent and 
36 per cent, for sand, clay, and humus soils respectively. It was 
further shown that the absorption and retention capacity of soil 
for toxins became generally higher the greater the content of 
humus. In concluding this part of the discussion it is well to 
