2 TOXIC SUBSTANCE EXCRETED BY PLANTS, 
Observations in the field were resumed in India, and these 
tended to very materially strengthen the view that materials 
injurious to other crops were excreted by the roots of certain 
common crops in India; this was especially the case with 
sorghum. The system of mixed crops very prevalent in the 
unirrigated tracts in India gave full opportunity for a number of 
observations to be taken, and on the strength of these, experiment 
was resumed both in the field and in water culture. 
Fistp EXPERIMENTS. 
The results of field experiments which commenced (in India) 
in the season 1903-04 were unreliable in the two following years 
owing to the failure of the monsoon. In the season of 1906-07, 
the rains were more nearly normal, and the following observations 
were made on the Surat Experiment Station ; they agree in kind 
and differ only in degree from those obtained in the previous year 
under a short rainfall. 
This Station is on typical deep black cotton soil and receives 
an annual rainfall of about 42 inches, all falling between the middle 
of June and the end of September. 
The soil is very retentive of moisture as will be obvious from 
the fact that cotton sown in June survives until the end of 
March, though no rain is received during the last six months 
previous to the final picking of the crop. The composition of 
this soil, as kindly analysed by Dr. Leather, is as follows :— 
MECHANICAL ComMPoSITION. 
Fine Gravel, 1 mm. a aes 460 Suan ae 
Sand, 1 mm, —0'2 Ao Ae ae dices @ wee 
<e 0'2—0'05 mm. ... aie nae Nene ae 
+ 0°05—'O0l mm. ... Sud wee erate) 
“ OL Ie ve xs 33 ve 820/58 
91°4 
Stones nie ep a oot poi 
Fine earth, 2 mm. ae ass Aid ssh, O04 
