320 BOTANICAL GAZETTE [NOVEMBER 
of acid than the dextrose. It will be noted that ; (0.7 per cent.) 
acetic acid proved fatal to the spores of Aspergillus used in this 
study, and in a 0.17 per cent. solution less than 1 per cent. ger- 
minated. 
The chloracetic acids—These acids are formed by the replace- 
ment of one, two,and three atoms of H, respectively, in the 
acetic acid radical by the element Cl; thus — 
pa th Li of 
S-G.00H = =-C-COH o-C-COH  GsGgue 
| | é 
CI Cl 
Acetic acid Monochloracetic acid Dichloracetic acid Trichloracetic acid 
It is a rule that the halogen substitution-products of carbon 
compounds have a toxic value which bears a close relation to the 
number of H atoms in the organic radical or hydrocarbon which 
have been replaced by the halogen. To quote from Davenport 
('97): ‘ Beginning with methane, CH,, we find this substance 
—marsh gas—innocuous when mingled with air. As the 
atoms become replaced by one or more Cl atoms, the poisonous 
properties increase,— 
CH, Cl is slightly anesthetic, 
CHCl1, = chloroform, 
CCl, is very dangerous, stupefying involuntary m 
Many such examples might be quoted, establishing this seo : 
was a matter, then, of great surprise to find what, at first sight, 
seemed to be a direct exception to this rule in the action of the 
chloracetic acids on the mold fungi. Their critical points wer’ 
determined as follows : 
uscles.” 
(Acetic acid - - - - 25.6 83 314) 
Monochloracetic acid - - 8.8 58 64 
Dichloracetic acid - - = 10.4 4 64 
Trichloracetic acid - - 37 sa oe 
lutions 
As soon as the experiment was complete the stock © d the 
used were placed in the hands of a chemist who aa 
potassium salt of each by just neutralizing with KOH. + 
fo 
salts are all quite highly ionized, the cathion being go a 
the anion the acid radicals of the respective acids. The 
