3 
= 
1898] GERMINATION OF FUNGUS SPORES 393 
start to resist the further action of the toxic solution. With 
Uromyces results were somewhat variable, but undeniable proof 
was obtained that growth is not prevented by ,%,. 
Ammonium hydroxid was tried only with Penicillium, and 
7 prevented growth. 
Potassium todid and bromid.—These agree in being non-toxic 
toward Botrytis, Macrosporium, and Uromyces at ¥%,, and to Peni- 
cillium at ,%. 
Sodium acetate-—This allowed growth of Botrytis, Macro- 
sporium, and Uromyces at +, and of Penicillium at normal, while 
z prevented Botrytis and Uromyces from growing. 
Magnesium sulfate, barium chlorid, ammonium chlorid, magne- . 
sium chlorid.— By two tests each, these all proved harmless to 
Penicillium at ¥%, strength. 
A general tabulation of these results is presented in table 
XVII which will be readily comprehended. The strength 
expressed represents the dilution of normal solution required to 
prevent most of the spores from germinating. If any growth 
occurred, there would be only a few isolated cases of germina-_ 
tion. In table XVIII the strength is indicated in parts per 
million. . 
The signs > and < are the common mathematical signs for 
“greater than” and “less than.’’ For example, the killing 
strength of KCN for Glceosporium is greater than ;/y, while that 
of potassium bichromate for Botrytis is less than ,f,- The 
molecular weight of the salt as used in making up the solutions 
is given, with formula of each substance. 
From the more interesting and important generalizations of 
this table a few may be indicated. 
Mercuric chlorid is by far the most poisonous substance 
used, while potassium cyanid has low toxic power. This may be 
partially explained by the evaporation of the potassium cyanid 
from the drop, but this explanation surely cannot apply in the 
