HOWARD AND HOWARD 31 
An examination of the table discloses several interesting facts. , As 
regards growth and seed formation, improved aeration by itself has had a 
marked effect. Seed production.was increased nearly three times and growth 
was almost doubled by the substitution of ten per cent of the volume of soil 
by potsherds. The replacement of half the soil by sand fed to a similar result. 
The greatest effects, however, were produced by leaf-mould with or without 
potsherds. The replacement of forty per cent of the volume of the soil by 
leaf-mould (30 per cen) and potsherds (10 per cent) increased seed production 
twenty-one times and growth more than tenfold: These results have been fre- 
quently confirmed both in the field and in other series of pot cultures. The effect 
of temperature is shown by the falling off in the rate of growth which took place 
_in all the pots after the end of November, no matter what the treatment. This 
always happens in the case of Java indigo at this time. After the end_ol 
November, no matter what the size of the plant may be there is practically no 
growth and no setting takes place during the cold months of December, 
January and February unless the temperature is much above the normal. 
An improved method of seed growing. 
The discovery of the factors underlying seed production enabled us to 
devise an improved method of growing indigo seed in Bihar. Instead of 
raising seed after leaf from a partially exhausted plant, it was found better to 
reverse the process and to raise a special seed crop which afterwards could be 
kept for leaf. For this purpose, the seed is sown early in August on specially 
selected high lying fields, known as dee fields. These fields must be above the 
flood level and they must have excellent surface dramage. They should he, if 
possible, near the banks of rivers so that the aeration of the soil is improved as 
quickly as possible when the water-level falls in September and October. To 
enable rapid growth to take place and to préserve the soil texture during the 
rains of August and September, the land must be well manured the’ previous 
_ May or June, with decayed organic matter and afterwards worked as a clean 
fallow. The crop should be sown in lines about three feet apart and particular 
care must be taken during the rains to break the surface crusts formed by rain 
as often as possible. This frequent harrowing is essential as the seedlings of 
Java indigo are very susceptible to poor soil aeration and are easily killed by 
surface crusts. After the last rains at the beginning of October, a final har- 
rowing is necessary, followed by deep cultivation between the lines to provide 
copious aeration for the intense nodular development then in progress. 
In addition to correct soil management, the object of which is to raise a 
large strongly growing plant by flowering time in mid October, particular 
