32 : BOTANICAL GAZETTE | JANUARY 
temperature, except with Gloeosporium, which refuses to germi- 
nate at so high a temperature. It is also doubtless true that 
other optimal considerations have a similar effect in increas- 
ing the resistance of plants to unfavorable conditions. It 
should also be noted in studying these results that several 
of the forms were tested in media prepared at different times, 
and as sugar beets vary in composition the media would vary 
somewhat in nutritive properties, and therefore in toxicological 
properties also, when used as a solvent for a poison. Making 
due allowance for these considerations, however, it is perhaps 
remarkable that of a selection of fungi representing fairly well _ 
the natural groups and including typical saprophytic and parasitic _ 
forms, the great majority of them should be found to be killed 
under similar conditions by concentrations of copper of between 
0.0099 z and 0.0168 », and that the three forms which were found 
to be markedly more sensitive (Rhizopus, Coprinus, and Chaeto- 
mium) should be of such diverse relationships. The two species” 
of yeasts proved to be equally resistant, although markedly dif- | 
ferent morphologically. The exact similarity of resistance was 
in this case very easily and prettily shown by growing both formle | 
in the same culture drop. Such a test is applicable only where 
the forms are of similar properties as regards resistance to t 
agent, time of germination, and rapidity of growth. Two cule 
tures of Penicillium glaucum, obtained from different sources ane 
presenting slightly different habits of growth, also ae t 
equally resistant. 
The great variation between the two symenoae aa 
partly to be accounted for by the fact that the medium was V¢ 
favorable for the development of Hypholoma, and only mode 
ately suited for Coprinus. The similarity of. resistance of 
four parasitic forms (at bottom of figure) is quite striking. 
will also be noted that they occupy an intermediate positi 
The most resistant forms will be seen to be the molds Asperg} 
lus, Sterigmatocystis, Botrytis, and Penicillium. 
Dr. Duggar has for some time been studying the b 
field of food relation to toxicology in general. It has bee 
