E. J. BTJTLER 25 



'■'.; The soil in Experiment VII was allowed to dry out more^or less com- 

 pletely (so far as the Bihar alluvium does so, which is only in the top few 

 inches) between December, 1912, and March 28th, 1913. It was verv much 

 drier than some of the lower levels of the swamp paddy soils of Eastern Bengal 

 at the same period. These may be still quite muddy at the end of February. 

 So also in Experiment X the soil was kept dry from February until the rains 

 in June. 



The experiments detailed earlier are strongly against any infection from 

 the soil being possible where standing water persists for several months after 

 harvest ; while those just described are applicable to the cases where the 

 fields dry out, as the great bulk of them do, in the early months of the year ; 

 but they leave open the question whether the worms may not survive in muddy 

 patches long enough to infect the succeeding crop. It has already been proved 

 that they can live for at least 4 months if kept damp but not immersed in 

 water, and this, combined with the fact that it is just in such muddy places 

 that the second growth from the aman occurs on which ufra has been found 

 as late as February, would be long enough for the purpose. But against this 

 it may be argued that these low-lying places are amongst the first to be flooded 

 by the rising water and such flooding would probably drown most of the worms, 

 already weakened by their long fast, before the humidity rose enough to allow 

 infection to take place. The problem presented by these muddy patches will 

 be returned to below. 



As regards seed infection, there is a good deal of evidence that it is not 

 common. Seed from an infected crop has been sown several times at Pusa 

 and at Dacca without causing an attack to develop. In Experiment VI the 

 infected seed was buried in the soil at the same time as the seedlings were 

 transplanted into the pots. The humidity conditions were such that the 

 worms on resuming activity in the wet soil (there was no free water standing 

 on the surface) could migrate to the seedlings. In another experiment 

 the infected seed was buried on December 1st, 1913, and standing water was 

 maintained for about 20 days, after which the soil was allowed to dry out for 

 18 days. On January 7th, 1914, 3 germinated paddy seedlings were sown in 

 the pot and no infection was obtained though they were kept in a saturated 

 atmosphere in standing water. In actual practice the conditions of Experi- 

 ment VI are probably never realized. Broadcasted seed is never sown during 

 the monsoon, but only in the earlier months when humidity is too low to 

 allow of migration of the worm. In the monsoon months only transplanted 

 paddy is put out and this could not carry contaminated seed. Again, in 

 Experiment XI, deep-water paddy from an infected field was sown on January 



