109] TOXIC EFFECT OF DELETERIOUS AGENTS 327 
different acids, as shown by their inhibiting and killing powers 
_ toward the spores of the five molds, are approximated. Too much 
importance must not be attached to the exact numerical value 
tere expressed for the different molecules, for several reasons. 
We do not know the reaction of the acids toward the nutrient 
medium in which we grow our plants ; we do not know the exact 
liect of the salts and sugars present on the ionization of the 
acids; and were it possible to eliminate every factor causing 
doubt or error, we should undoubtedly find the relative toxic 
operties of the molecules varying with almost every plant 
tested. Let me repeat: the exact numerical values here given 
uenot significant. The order and general proportions of these 
talues ave significant. The emphasis is laid on part I of this table 
for reasons already given, 
Line 1 gives the strength of the various acids required on an 
 Ntrage to inhibit germination. Line 2 is developed from line 1. 
It gives the relative toxic properties of the acids expressed 
/Merically, HCl being taken as 100 for a basis of comparison. 
iM ionized and un-ionized portions are considered separately, 
: ines 4, 5, and 6 being devoted to the former, and 7, 8, and 9 to 
the latter, Line 4 gives the toxic value of the cathion in units 
E ionic i; line 5 that of the anion. Line 6, being the total of 
: ne 5, Sives that portion of the total toxic value of the acid 
" eto be attributed to ionized portion. Line 7 gives the 
tl units.” In other words, that part of the total toxic 
se be accounted for by the un-ionized portion. Line 8 gives 
_,, Ptcentage of such un-ionized molecules present at the inhib- 
_ SPoint. Line 9, the quotient of the residual units divided by 
{itrentage of un-ionized molecules, gives in terms of ionic H 
2 ‘oxic value of the different acid molecules. 
Il is worked out similarly, and has reference to the 
ear “ the acids towards the molds, as shown by their power 
ey the Spores 
: [ Zo be concluded. | 
