132 
FIFTEENTH REPORT. 
to learn what relation exists between two poisonous substances when 
one is a known narcotic. For these experiments, copper sulphate was 
used at concentrations varying from M3 x It)- 4 to M2.5 x 10-° together witJi 
the non-volatile anaesthetic chloral livdrate in concentrations varying 
irom jjr-j- to Garden peas of the variety of Little Gem were se- 
lected as indicators, and the increase in length of the roots afforded 
the criterion as to the effects produced by the toxic substances. For 
a criticism of ibis criterion, see Heald. 13 Five seedlings floating on 
paraffine discs were grown in each dilution so that the roots 
were the only portions of the plants exposed to the solutions. 
While the number of plants used appears small, the work has 
been repeated three times with concordant results. In the 
series, run in duplicate, from which the curve is plotted, copper sul- 
phate M 51000 and chloral hydrate M/165.5 were each diluted by the 
addition of 50, 100, 150 cc., etc., of water to 450, 400, 350 cc., etc., 
respectively, of the original solutions. Then the copper sulphate was 
mixed with chloral hydrate to form another series by the addition of 50, 
100, 150 cc., etc., of CuSO 4 to 450, 400, 350 cc., etc., respectively, of 
chloral hydrate. 
Observations were made at the end of twenty-four and forty-eight 
hours. The average increase in the length of the roots in each dilution 
was chosen and the results plotted. The curve shows clearly the poor 
growth in the solutions where the single substance was used, except 
at the lowest dilutions, and a noticeably better growth where the two 
substances were combined. Antitoxic action of the combined solution is 
especially noticeable in the central part of the curve where the amounts 
of the different solutions are nearly equal. • One further statement may 
be made, namely, that according to the accepted dissociation theory, we 
may look upon the compounds in these dilutions as completely dis- 
sociated. and it seems also safe to conclude that since there is an ab- 
sence of reaction between copper sulphate and chloral hydrate at ordi- 
nary and even at high temperatures according to Werner, 14 there is no 
chemical reaction between the two compounds as they have been used. 
The results of these experiments with pea seedlings show that we are 
dealing with a case of antagonism between a salt and an anaesthetic. 
Chloral hydrate thus exhibits an antitoxic action which though less 
marked may be comparable to the antitoxic influence of calcium over 
magnesium salts. It is interesting to note that the use of anaesthetics 
on plants gives results comparable to some extent to those obtained by 
Lillie with lower animals. 
A number of theories have been brought forward to explain the 
mechanism of antagonistic salt action. No detailed account can be at- 
tempted here, but it might not be out of place to outline the avenues of 
attack. First, the effect may come about through reactions in the 
liquid itself. These may be due to chemical reaction or chemical affinity. 
A proper choice of materials, however, eliminates many of these cases 
and under this head we need consider only such effects as do not come 
about in that way. 
The extent of ionization is perhaps the problem which is most im- 
portant in this connection. If we look upon the molecule as compara- 
,a Heald F. D.. Bot. Gaz. 1896, 22:125-153. 
^Werner, E. A., Jour. Chem. Soc, 1901, 85:1376-1381. 
