THE TOXICITY TO FUNGI OF VARIOUS OILS AND SALTS. 7 
hemp and cotton fibers, and starch grains, comes under the general 
term " adsorption." It is often explained as a direct physical 
affinity of the toxic chemical for the inert substance; that is, a con- 
densation of the substance on the surface or in the interstices of the 
insoluble matter, or the formation of a solid solution of the two, but 
chemists and physicists are not at all in agreement in regard to these 
explanations. 
Among others, True and Gies (29) and True and Oglevee (31) 
worked upon this problem, using seedlings of Lupinus albus and a 
number of inorganic and organic compounds. As adsorbing agents 
such substances as sand, glass, filter paper, and paraffin were applied. 
With copper sulphate they found that at least twice the usual toxic 
concentration could be endured by the Lupinus roots when a suf- 
ficient quantity of the insoluble matter was added to the hypertoxic 
solution. In summarizing their work they remark: 
It appears in general that the presence of a considerable body of certain insoluble 
Bubstances in solutions of strongly toxic compounds both organic and inorganic in 
their nature, be they electrolytes or not, tends to decrease the toxic activity of the 
solutions in question. On the whole this ameliorating action is more clearly marked 
in case the poisonous solutions concerned are dilute solutions of strong poisons than 
when relatively concentrated solutions of weaker poisons are concerned. 
Fitch (8) conducted a series of experiments with sulphuric acid 
and copper sulphate, using pottery, glass, sand, and filter paper as 
the adsorbing agents and two common molds (Aspergillus niger and 
Penicillium glaucum) as the test organisms. She established for fungi 
the same phenomena of dilution that a number of other workers had 
found to hold for flowering plants. 
The diversity of results secured when toxic substances are tested 
on various media, particularly such as contain starch grains and 
similar materials in suspension, no doubt is explained, in part at least, 
on the basis of adsorption. 
RELATION OF TEMPERATURE TO FUNGOUS GROWTH AND TOXICITY. 
It is well known that temperature exerts a vital influence on the 
growth and development of fungi. Not alone is the temperature 
range which permits the growth of the organisms highly variable, 
but also the optimum temperature in many cases varies for the differ- 
ent species. Thus, for nine species of wood-destroying fungi studied, 
Falck (5, 6) indicated a growth range lying between 3° and 44° C, 
with the corresponding optima between 18° and 35° C. For Meru- 
lius domesticus ( = M. lachrymans in part) this optimum falls between 
18° and 22° C. 1 ; for Coniophora cerebella, 22° to 26° C; for Polyporus 
vaporarius spumarius, 26° C; for Lenzites abietina, 29.5° C.; for 
* Hoffmann (13) states that under certain conditions of culture this optimum may be raised so as to 
fall between 18° and 26° C 
