1906] BROOKS—TEMPERATURE AND TOXIC ACTION 36 
finally in distilled water. They were dried from alcohol and made 
up in the usual manner. The covers were treated as the cells, except 
that in each instance they were heated for a longer time, and that 
they were given one or two final boilings in redistilled water. All 
flasks, vials, etc., used in these experiments were cleaned with alkali, 
acid, and distilled water by boiling, as described for the cells. 
As a culture medium several vegetable decoctions were tried. It 
was found that the five fungi used in these experiments grew well 
upon decoctions made from onions, beets, tomatoes, grapes, pars- 
nips, beans, mushrooms, and sugar beets. Several series of experi- 
ments were made with tomato decoction as a medium, but it was 
found that a sugar beet solution gave less precipitate in the presence 
of CuSO, and was in general more satisfactory for the work. In 
all the experiments reported in this paper beet decoction was used 
as the nutrient medium. In making the infusion 600 grams of beets 
were used for every liter of water. At the time of using, the decoc- 
tion was diluted, by the addition of the toxic solution and water, 
to one-half of its former nutrient value. 
The toxic agents used were HNO,, H,SO,, and CuSO,+5H,0. 
The chemicals were of the highest quality that could be obtained 
and the acid solutions were standardized before using. It is a well- 
known fact that strong concentrations of CuSO, precipitate proteids, 
In solutions at ordinary temperatures in which both are present, this 
precipitation continues for a long time, thus continually changiag 
the nature of the liquid. Therefore, as it was necessary to make 
experiments at considerable intervals of time, the toxic agent was 
hot added to the beet decoction until the time of its use in cultures. 
Stock solutions of the chemicals were made in water that had been 
carefully redistilled from glass ‘in the presence of an oxidizing agent. 
ormal or one-half normal solutions were made and these stored in 
flasks provided with closely fitting rubber stoppers. By means of 
4 series of graduated vials, these stock solutions were diluted and 
mixed with the beet decoction at the time of using. 
The fungi used were Botrytis vulgaris, Monilia fructigena, Stertg- 
matocystis nigra, Mucor Mucedo, and Penicillium glaucum. The 
first two may be and usually are parasitic, and have an optimum 
temperature that is comparatively low; the last three are saprophytic 
