CO 
TOXIC SUBSTANCE EXCRETED BY PLANTS. 
eases. The whole difference is, however, due to last year’s crop- 
ping, series I being then under sorghum and series II under 
cotton except plots 11 and 14 which were fallow in both series. 
This accounts for the great difference in the yields of the northern 
halves of plots 1 and 2, 24 and 25, sorghum yielding much better 
after cotton (series II) than after sorghum (series I). The con- 
verse might appear to be the case with cotton which in series II 
(after cotton) has yielded less than in series I (after sorghum), 
and the whole might appear to be an example of the benefit of 
rotation. The small yield of cotton in series II is, however, due 
in part at least to the more vigorous growth of the sorghum with 
which it was sown as a mixed crop and only to a small extent to 
the fact that the preceding crop was cotton. 
Water CuLturgss. 
A large number of experiments in water culture were started 
some years ago. It is unnecessary to give the preliminary 
investigations on this point. The greater part of the results 
obtained by me have been brought together for a final test during 
the last few months, and these only will be here recorded. 
Preparation of Solution of Excreta. 
In December last, final water cultures were started on the 
Dharwar Experimental Station in a number (in all 20) of earthen- 
ware dishes (12 inches in diameter and 4 inches inside depth). 
In each of these dishes 4 litres of well water was placed, and over 
this a circular teak board perforated by 90 holes, + inch in 
diameter, was supported by strings, to which were attached 
counterpoise weights hanging over the outside of the dish. 
Seeds were germinated in crushed quartz, and when the radicle 
was about an inch long, were transferred to the water culture 
dishes ; a radicle was passed through each hole in the board 
and held in place by a small wad of cotton. In each 4 litres of 
water therefore 90 seedlings were planted ; those that failed were 
replaced by others. 
