56 E. J. BUTLER. 
the soil to surrounding plants has not time to occur to any great 
extent. 
There is no definite evidence that the disease is conveyed in 
the seed, and this appears to be unlikely. The control plants in 
the earlier series, before seed disinfection was practised, indicate 
that it does not happen commonly. 
To determine the exact locality of infection a series of water 
cultures was tried, the plants being germinated under sterile condi- 
tions, and transferred to plugged sterile cylinders containmg von 
Crone’s solution,’ when the shoot was from 1} to 2 inches high. 
Arrangements were made for daily aeration of the solution and stir- 
ring up the precipitate of salts. The moculations were made from 
a glucose agar culture. The results bore out, what was already 
fairly evident from examination of the pot cultures, that infection 
begins ordinarily through the fine lateral roots. These were rapidly 
attacked and shrivelled, whether they arose below the seed, or 
above it, in those cases where the seed was well below the cork. 
On the other hand, moculation of the stem gave no result, nor did 
one or two inoculations made on the main root just below the seed 
and above the origin of the first lateral root. The water cultures 
were remarkable in some respects. Though infection occurred on 
the white lateral roots, even more than an inch behind the growing 
point, provided the part inoculated was above the level of the solu- 
tion, none occurred in any case below the liquid. The filaments in the 
former case penetrated the cortex and led to browning of the cortical 
cells, visible externally as a distinct brown mark at the point of 
inoculation. They did not, however, reach the vascular system, 
no case of penetration of the central cylinder having been observed. 
Hence there was no stoppage of the upward current and death did 
not result in any of the six plants inoculated at the roots, though 
two of them shed many of their leaves and looked very pallid, and 
a third was less markedly affected. In two of these the observa- 
tions extended for over three months, in the other four for two 
{ Potassium nitrate 1 grm., ferrous phosphate ‘25 grm., tri-calcic phosphate ‘25 grm., 
magnesium sulphate *5 grm., calcium sulpbate + grm., water 1 litre. 
