58 
TENTH REPORT. 
ON THE TOXIC ACTION OF BORDEAUX MIXTURE AND OF CER- 
TAIN SOLUTIONS ON SPORES OF FUNGI. 
J. B. Dandeno. 
The spores of a fungus are usually by far the most resistant portions of 
the fungus-plant, not only to poisons, but also to various other injurious 
factors of environment. And, as might be expected, the spores of one 
species may differ in resisting power, very materially, from those of another 
species. So that it can scarcely be predicted what will happen in one case 
from what happens in another. 
The objects of the experiments here described were to determine the resist- 
ing power of some of the common forms of fungi to certain toxic solutions, 
and also to Bordeaux mixture, seeing that Bordeaux mixture is a substance 
so commonly used as a remedy for plant diseases. 
The species made use of were Penicilium glaucum, Puccinia asparagi, 
Macrosporium nobile, Ustilago maydis, Glomerella rufomaculans (Bitter 
rot). The toxic substances employed were NaOH, KOH, HC1, H2SO4, 
C11SO4, and Bordeaux mixture. In all these substances, excepting the 
last, fractions of normal solutions, as indicated in each case, were taken. 
In C11SO4, water of crystallization, and the fact that it is dibasic, were of 
course taken into consideration. The method employed to test germination 
was simple and certain. A drop of the solution was put upon a slide, and 
in this drop were placed spores of the fungus which were to be tested. This 
preparation was then set away in a moist chamber to prevent evaporation, 
and left there. The slides were then examined from time to time and records 
made. The test was, therefore, as to whether the spore was able to ger- 
minate and send out a hypha while actually immersed in the liquid. If 
the spore germinated, it seemed conclusive proof that the fungus could tolerate 
this poison, more particularly because the first hypha sent out by the spore 
is very sensitive. The spore itself, being usually very resistant because of 
its thick wall, and other qualities, might easily withstand much stronger 
solutions than those used, especially if the spores happen to be in a dormant 
state. But it was the mycelium, and not the spore, that- was tested. 
As Bordeaux mixture is composed of a liquid and of a solid (in very small 
particles), two conditions require attention, (1) the liquid without the 
solid, (2) the solid and liquid mixed. The latter is, of course, the form used 
in spraying for fungus diseases. 
The Bordeaux mixture was prepared from the general formula, 4 lbs. 
crystalline copper sulfate, 4 lbs. fresh lime, and 40 gallons water. It 
was found, however, that much more lime than this was required to 
neutralize the copper in the solution, so that in the supernatant liquid, 
when treated with potass-ferro-cyanide, no reaction resulted. The Bor- 
deaux mixture actually used contained approximately 6 lbs. lime, 4 lbs. 
copper sulfate, and 40 gallons water. The strongest solution employed in 
these tests was a double strength of Bordeaux, i. e., 6 lbs. lime, 4 lbs. 
copper sulfate, and 20 gallons water, and from this stock the following 
grades of dilution were made: — 2, 1, \ , £, T l B . The first here 
