392 BOTANICAL GAZETTE | [DECEMBER 
being fatal to Sterigmatocystis and es to CEdocephalum. The 
others are more resistant. It is, however, more toxic to alge 
(Bokorny, ’86) than to molds, and Ciliata are even more suscep- 
tible. Paneth (’89) found a .005 per cent. solution to be the 
limiting line for the latter. 
Commercial preparations of H,O, vary very greatly in the 
amount of H,O, in solution. A true ten-volume solution 
should yield, when fully decomposed, ten volumes of O, and 
should contain by weight 3.04 per cent. H,O,. The preparation 
used in this study although “ fully guaranteed,” etc., contained 
but 2.59 per cent. H,O, on being tested. 
SULFATES OF THE STRONGLY-TOXIC METALS. 
These salts are arranged in the order of their toxic properties 
towards molds in the following list : 
Nickelous sulfate, NiSO,; 4.8, 33.6, 1155. 
Cobaltous sulfate, CoSO,; 6, 57.6, 389. 
Ferrous sulfate, FeSO, ; 14.4, 775, 2150. 
Copper sulfate, CuSO, ; 8.4, 7377.2, 582. 
(Copper nitrate, Cu(NO,),; 8.4, 234, 634.) 
Zinc sulfate, ZnSO, ; 26.4, 602, 3072. 
_ The data regarding the ionizations of these salts are rather 
‘meager. They are, however, not greatly different in ionization 
at similar concentrations. This is about 40 per cent. to 44 P® 
n ‘ 
cent. at ee concentration (Whetham, ’95, pp. 218-276). 
Nickelous sulfate—The different molds exhibited more vari 
tions in their specific resistance to this agent in regard to the 
: n 
death point than was observed with any other. 3 proved fatal 
to Botrytis, while Aspergillus failed to lose its vitality 1n 4 
normal solution (containing over 13 per cent. ant 
NiSO,) for 48 hours. Much less variation was shown 10 . 
inhibiting powers. Aspergillus and Penicillium germinated . 
Mi Woe: : 
aa 266 inhibited Botrytis. The fact that 32 times the strength 
