Brenchley.—-Organic Plant Poisons. II. 273 
Pyrogallol. 
Owing to shortage of the supply it was only possible to test the effect 
of pyrogallol and phloroglucin upon peas. Pyrogallol was very poisonous, 
the toxic effect being noticeable with comparatively low concentrations 
(Fig. 15). High strengths killed the plants outright, and rather lower 
strengths allowed of well-marked root recovery. The poisoned roots became 
intensely black in colour, so that when recovery set in the contrast between 
the black root and the fresh white laterals was very marked. Decom¬ 
position of the solution took place very rapidly. The stronger solutions 
became very yellow and developed 
much heavy black or dark brown 
precipitate. The discoloration of 
the roots was still noticeable in the 
presence of so little pyrogallol that 
the solutions themselves were not 
turned but retained their usual 
colour. The mould development 
was rather unusual, as fungus was 
evident in the precipitate as well 
as floating on the surface of the 
solution. That among the preci¬ 
pitate included a chlamydospore 
condition of a Nectria , possibly 
N. cinnabarina , Fr., and a myce¬ 
lium which was producing myriads 
of budding conidia. The surface 
mould was a starved condition of of pyrogallol. Oct. 9, 1914-Jan. 19,1915. 
Penicillium glaucum , Link. 1 
Phloroglucin. 
This proved to be somewhat less toxic to peas than the pyrogallol 
(Fig. 16). No change occurred in the colour of the solution and the roots 
that were killed turned yellowish, without darkening much. After the 
moribund shoots lost their green colour they took on a curious reddish- 
brown colour in their stems, and the leaves turned brownish. Plants with 
M/ioox|- did not show the usual phenomena of arrested growth followed 
by later recovery. Instead the laterals were formed at the beginning, but 
made very poor growth above the solution, and very little in it. Later on, 
they grew out but were short, and became thick and yellow, and still later 
they became spindle-shaped, being stubby and thickened in the middle. 
The roots eventually blackened, and retained their abnormal character to 
the last, though they developed a few straight greyish-white laterals. With 
1 Moulds identified at Ivew by the kindness of the Director. 
T 
Tot all 
SKooV 
"RooV 
1 - n * 4-6 
loo a 
Fig. 15. Average dry weights of ten 
