206 
Journal of Agricultural Research 
Vol. XXI, No. 4 
In seeking for an explanation of the increase or decrease of the osmotic 
concentration by the different organisms in solutions containing the 
same percentage of sugar, one should take into consideration the cleavage 
products formed. Many investigators have shown that some fungi, 
and it may apply to all, have the power to produce organic acids, alcohol, 
etc. Wehmer (30) gave the generic name Citromyces to a group of 
fungi which he believed to be characterized by their ability to produce 
citric acid. Oxalic acid fermentation was thought by him to be a 
characteristic of Aspergillus niger. Currie (4) some years later showed 
that citric acid was likewise produced by A . niger in nutrient solutions. 
Lind ( 21 ) showed that oxalic acid was produced by Aspergillus niger , 
Penicillium glaucum , and Botrytis cinerea, and Lafar (rp, p. 331) by A. 
niger. Lafar also found that citric acid was formed by Citromyces 
pfefferianus Wehm., C. glaber Wehm., and P. luteum. Many other 
references might be cited to show that a great variety of fungi and 
bacteria produce acids of various sorts. 
The production of alcohol has been proved to be a regular phenomenon 
of many fungi, the amount formed depending on the substrate, the 
temperature at which incubated, and the length of the incubation 
period. 
Gayon (jo), Hansen (12), Fitz (9), and Brefeld (2) showed that 
Mucor spinosus v. Tieg. and Rhizopus nigricans produced alcohol in 
varying amounts, depending somewhat upon the conditions mentioned 
above. M. racemosus produced alcohol but little when incubated at a 
temperature below 15 0 C. R . nigricans ceased to produce alcohol when 
1.5 per cent had been formed. M. spinosus , according to Gayon, will 
produce as much as 1.5 to 2 per cent, and M. erectus Bain, as much as 8 
per cent, according to Hansen, when incubated at room temperature. 
If either alcohol or acids or both were formed in the solutions the osmotic 
concentration would be influenced in proportion to the amount pro¬ 
duced. Previous tables have shown that the percentage of sugar was 
lowered by the fungus, and yet in spite of that the osmotic concentration 
of some of the solutions is actually higher than that of the controls. 
This would be possible only in case some of the sugar or other constitu¬ 
ents of the substrate were converted into some substance, such as alcohol 
or organic acids, which would affect the osmotic concentration. In 
M. racemosus the osmotic pressure of the solution of the inoculated flask 
is higher than in the control, although a considerable amount of the 
sugar was actually removed. This organism is one which is known, as 
pointed out in one of the citations given above, to produce a considerable 
quantity of alcohol. Data presented in Table II show that Diplodia 
tubericola , M. racemosus , and Sclerotium bataticola growing in an approxi¬ 
mately 10 per cent solution reduced the sugar from 14.26, 14.34, and 14.48 
to 1.29, 7.60, and 3.18 gm., respectively. On the other hand, the osmotic 
pressures of these solutions were changed from 16.24, 16.84, and 16.12 
