The Action of Poisons upon Chlamydomonas 
and other vegetable Cells. 
BY 
H. W. HARVEY. 
Downing College , Cambridge. 
i. The Toxic Action of Various Isomers upon Vegetable Cells . 
T HE toxic action of dilute solutions of the isomers of various benzene 
derivatives upon the roots of young lupine plants has been studied 
by Hunkel and True , 1 and also the effect of a small number of these isomers 
upon Spirogyra. The toxic activity in these cases does not depend upon 
the hydrogen ions, for the dissociation in each case is shown to be too slight to 
have any very appreciable effect. Hunkel and True determined the minimal 
concentration of the isomers required to kill practically all the young lupine 
roots immersed in them within forty-eight hours ; these concentrations, 
expressed in gramme molecular weights per litre, are shown for a few cases 
in the second column of Table I. From a comparison of these concentra- 
tions it is seen that f the toxic power of the para-derivative is in most cases , 
but not invariably , much greater than that of the ortho - or meta-derivative \ 
This conclusion was previously arrived at for bacteria by Carnelli and Frue , 2 
who experimented with gelatine plates containing various concentrations 
of the isomers, which were exposed to the air of a dusty room in order to 
inoculate them. 
In the third column of Table I the order of toxic strength of the 
poisons is given ; these were obtained, for the cresols by Frankel and for the 
phthalic acids by myself, by adding a drop of a culture of the bacteria to 
a tube of dilute poison, and inoculating tubes of suitable media from this at 
regular intervals. 
I have investigated the effects of these isomers upon Chlamydomonas , 
and determined the minimal concentrations of the various isomers required to 
cause cessation of movement in a culture of actively motile Chlamydomonas 
multifilis in ten minutes. These concentrations are given in the first column 
of Table I. It was found possible to estimate the concentrations required 
1 Hunkel and True : Botanisches Centralblatt, B. 76, pp. 231, 289, 361. 
2 Carnelli and Frue : Journal Chemical Society, vol. 57, p. 636. 
[Annals of Botany, Vol. XXIII. No. XC. April, 1909.] 
