34 BOTANICAL GAZETTE [JANUARY 
time, however, perhaps weeks, for all this copper to find its way 
into the spores. Should the medium be such as admitted 
growth, the production of protoplasm might easily offset its pre- 
cipitation by the copper, and long before the copper could have 
its maximum effect the protoplasm would have increased mani- 
fold, and would require a corresponding increase in the con- 
centration of copper to cause death. Thus it is that with j 
every favoring influence the fungus can make a better fight for : 
life. 
The results given in fig. 2, with various media, and with © 
copper in the form of the sulfate, are those with Gdocephalum ; 
albidum. The work repeated with Rhizopus nigricans gave essen- — 
tially the same results. A single glance at the figure shows how — | 
much more toxic the copper proved to be when dissolved in pure 
water than when in any other medium, 0.0002 ~ being fatal in 
twenty-four hours. This is but one-fortieth of the concentration — 
of copper required to give the same result in a decoction of = 
sugar beet. When I.5 per cent. asparagin was added to this — 
beet infusion the toxic value of copper dissolved in pure water a 
was to its value in the asparagin-beet medium as 142: 1, and the . 
comparison in the case of the medium compounded from aspara- : 
gin and inorganic salts the ratio is 285:1. In this last case 
there was a slight precipitate noticed under the microscope, and : 
it may be that some of the copper was precipitated by the phos- 
phoric acid present. Exactly what proportion of this striking 
difference is to be assigned to the nutritive condition and what to 
chemical and physical transformations it is impossible to say 
changes. That these changes have a preponderating influence 
in the case of the beet decoction is also very probable. The 
experiment of diluting and concentrating the beet decoction 
seems to support this view. The values of the triple, the ordi- 
nary, the half, and the quarter strengths are not greatly different 
