36 BOTANICAL GAZETTE [JANUARY 
so far as stimulation of germination and early mycelial develop- 
ment is concerned. The same is true of the beet decoction to 
which the asparagin was added. Yet we have the following — 
variation in the lethal concentrations: 
Pie Relative pee Cu 1 
: thal required to inhibit as 5 
Medium concentration compared with a pure d 
water solution 
Beet decoction, normal strength............. 0.0076 # 38 times 
hg Ls, iluted to two volumes....... 0.0054” 27 - 
: " hI coh ate egy 9 aa a 0.0034” i 
“3 1 evaporated to % volume...... 0.01632 $2... 4 
4 " + 1.5 per cent. asparagin.... 0.0284 ” Taz 
Were it wholly a matter of food relation we should expect 
the figures in the third column to be near 38 in each case. 
Were it wholly a matter of the chemical or physical transforma- 
tion of the copper by the compounds present in the beet decoc- — 
tions, we should expect a more proportionate decrease in the — 
first three numbers of the third column, corresponding to the 
dilution of the medium by the added pure water. As already — 
remarked, it is not possible to determine with any degree of 
precision the part played by any one factor from the data at 
hand; but it is evident that with different media great differ- 
ences in the toxic value of the copper may be obtained, and that 
asparagin has the power of uniting with salts of copper in such a 
way as to reduce their toxic properties in a very extraordinary — 
manner. It is of interest in this connection to note that mercuri¢ : 
chlorid is not similarly reduced in toxic properties by the pres | 
ence of asparagin.’° 3 
Fig. 3 presents the results of some studies on the addition of . 
certain compounds to pure water solutions of some copper salts. 
Here the results given are with CEdocephalum, and, as in fig. 2 
the results were checked over with Rhizopus nigricans. 1n this 
diagram the vertical lines representing the variation in the cons | 
centration of copper present in the different cultures show 47 — 
increase of 30 per cent. for each division over the last preceding — 
* Jour. Phys. Chem. 5 : 302, 1901. 
as 
