HOWARD AND HOWARD 23 
able to survive the rainy season. The stoppage of selection, the mixing of 
kinds which is such a characteristic of native agriculture and the resulting 
crossing with types which do not suit Bihar soon completely altered the bota- 
nical composition of the crop and rendered it unsuitable for growth under 
monsoon conditions. Indigo wilt is, therefore, another example of degeneration 
through vicinism. 
IV. THE REMEDIES AGAINST WILT. j 
Now that the nature and cause of wilt have been discovered, the question 
of remedies can be considered. Wilt has arisen from unrestricted natural 
cross-fertilization which, in the course of time, has completely altered the 
original type which did so well in Bihar. This crossing with annuals 
combined with the complete cessation of selection has lowered the general 
vigour of the crop, has rendered it much more susceptible to waterlogged 
conditions and has altered the type of root-system. The problem is now to 
recover by selection the original type which suited Bihar conditions and to 
maintain it by continuous selection. The maintenance of the type will pro- 
bably prove to be the most difficult portion of the work. : 
Java indigo only sets seed if visited by bees and the crop is a mass of freely 
crossing heterozygotes. If grown from self-fertilized seed, there is a rapid 
loss of vigour through self-sterility. The ordinary methods of selection, 
therefore, do not apply. Crossing can only be controlled, it cannot be pre- 
vented. To maintain the type required, constant selection will be essential 
and the greatest attention will have to be paid to seed growing. The present 
- practice of importing into Bihar any kind of seed which happens to be offered 
for sale, will have to be given up and arrangements will have to be made to 
grow all the seed required locally and to carry out the necessary selection on 
the estates themselves. 
Selection. 
A considerable amount of selection work has been done on the ordinary 
indigo crop and on the samples obtained from Java. Several of these selections 
have already been tested on an estate scale. Three types have survived the 
early trials and have been retained for further work. These are as follows :— 
Type 10. A mixture of quick growing early maturing forms selected 
from the seed imported from Java in 1916. The selection work in progress 
on this type promises to isolate a type of Java indigo which might replace 
Sumatrana. Sufficient seed has already been obtained for trials on an estate 
scale which have been arranged for. 
Type 15. This is a somewhat bushy indigo with surface roots which 
shoots well after the first cut and which seeds well in Bihar. It is now éeing 
