E. J. BUTLER 11 



for 15 weeks uncoiled slowly to about half of full extension when placed in 

 water. The body was highly vacuolate — indeed almost empty — and no other 

 motion was observed in 18 hours. Yet on adding weak picric acid slight 

 recoiling, to about half the original coil, occurred. Other worms from the same 

 batch decomposed in a few days after uncoiling in water, so that if not dead 

 they were at least moribund. Worms liberated in such a condition in a flooded 

 paddv field would be quite unable to reach the paddy plants or to climb up any 

 that they accidentally come in contact with, so that for practical purposes, 

 in considering the period during which desiccated worms are capable of 

 reinfecting the crop, the resumption of active motility may be taken as a 

 measure. This period exceeds the time required to fill in the gap between 

 the harvest of the aman paddy and the first records of the disease in the aus. 

 Thus worms dried out on their host plants by digging up the latter and 

 removing to the laboratory in the second half of November, 1916, resumed 

 active motility on being placed in water early in June, 1917. The power of 

 uncoiling in water persists much longer, for at least 15 months, but I have 

 not observed active motility after so long an interval, nor would the worm be 

 ever likely to require such a period of rest in the paddy plains of Eastern 

 Bengal before finding conditions of moisture and fresh food which would 

 enable it to resume its active parasitic life. 



Life is not so prolonged when the worm is totally immersed in water. 

 Many die in a few days but some may survive for more than a rrronth. The 

 following experiments iii 1913-11 illustrate the variations observed. On 

 September 8th, 1913, a number of active worms in aM stages were sown in drops 

 of rain water on 4 slides and kept in a moist chamber. The majority were 

 motionless and apparently dead 5 days later. In 11 days all were dead on 

 2 slides, but a few were still motile on the other 2 slides. The dead ones 

 decomposed gradually and all had decomposed by December 1st when the 

 slides were again examined. On October 9th, 1913, several more slides were 

 similarly prepared but tap water was used. All were dead and decomposing 

 by December 1st {i.e. in 52 days). On December 1st, 1913, another batch 

 of 3 slides was prepared in the same way as the last. Many of the worms in 

 all stages were alive and motile after 24 days and about 50 (mostly adrrlts and 

 mediuirr-sized larva?) after 5 weeks. On January 0th, 1914, from 20 to 30 

 active worms (mostly larva3) were sown in a glass capsule in distilled water 

 with some germinated paddy seedlings. The seedlings were removed 

 after 4 days, with one or two worms that had climbed up them. Of 

 those left in the capsule (over 20) only one living could be found on 

 January 26th. 



