6 TOXIC SUBSTANCE EXCRETED BY PLANTS, 
expect that if in two species of plants one was the more resis- 
tant to a given quantity of sorghum excrement, yet the other 
might be the more resistant to the excrement from, say, cajanus. 
This has, however, been observed to be the case neither in the field 
nor in water cultures. 
Further, the amount of substance excreted (per unit area of a 
field sown under the conditions of the experiment) by the various 
crops appears to be in the same order. For, reading the columns 
of Table II horizontally, we find that sorghum excretes an 
amount of substance which reduces its own yield by 55 per cent., 
while cajanus excretes an amount that reduces the yield of sor- 
ghum by 25 per cent., cotton an amount that reduces the yield of 
sorghum by 18 per cent. The regularity of the table as read 
thus horizontally may, however, be deceptive. 
On the Dharwar Experimental Station a few observations 
(on other crops) were made, which indicate that gram (cicer) is 
about equally sensitive and equally toxic with wheat, that both 
are equally sensitive with sesamum but less toxie than the latter, 
while linseed is similar to cotton in both respects except perhaps 
that it is more sensitive. 
In the experiment where cotton and sorghum were grown 
in alternate rows (2 feet apart) the following results given 
below in Table III were obtained. The figures are so remarkable 
that they are given in full. The experiment was made on 
1-acre plots, each 191 yards long and 64 yards wide, of which 
the record is known since 1897-98, when my predecessor, 
Mr. Mollison, laid them out for an excellent series of rotation 
and manure experiments. In numbering the rows, the numbers 
of the rows go in the same direction as the numbers of the 
plots themselves, so that the first row of a plot borders on the 
plot whose number is next lower and ata distance of 3} feet 
from it. The relative positions of the different crops will be 
obvious from the accompanying plan of one of the plots in which 
dotted lines represent rows of cotton; continuous thin lines, 
rows of sorghum; and continuous thick lines, the border of 
the plot. 
