any given time, and still more out of the question to follow the 

 variations in temperature through which it passes during its transit 

 through a hot-air machine. It has been found in practice that the 

 most comparable results are obtained by registering the temperature 

 of the seed immediately after leaving the machine, lii the majority 

 of machines tWO exceptions to this are discussed below the seed 

 is then at its maximum temperature and the worms may be regarded 

 as being at as nearly as possible the same temperature. The time 

 during which the worms remain at, or near, this temperature depei 

 not on the time taken to pass through the machine, since during this 

 time the seed is not remaining hot but is being gradually heated 

 much as on the treatment of the seed after leaving the machine. 

 If sacked immediately, the seed cools at an astonishingly slow n 

 the temperature only falling one or two degrees per hour. If. on tin- 

 other hand, the xposed to the air in a thin layer immediately 

 after treatment, the tempo may fall well below the minimum 

 fatal temperature in less than half a minute. 



The necessity for bearing the.-. m mind and the dillicultv 



of giving a satisfactory reply to the question postulated above, are 

 well illustrated in Table I. which shows the mortality of the worm> 

 at different temperatures with various methods of treatment. The 

 temperature in everv ca temperature of the >eed immediately 



after treatment. A black line has been drawn on the right-hand 

 side of every column as far .ninimum temp- 



a regular mortality of !).") per cent or more. It will be seen at 

 that the tops of the bhick lines in the dilVerent columns vary in position 

 from 47 to GO" ('. What, then, are the causes of these discrepancy 



In the first two columns are given the figures from some e.x: 

 ments in which small bags of infected cotton seed were dipped, for 

 one minute in one ca.se. and for live minutes in the other, in hot water 

 at various temperatures. After treatment tin- iieing in a small 



mass and covered with water, cooled rapidly. It will be noticed that 

 with the one minute treatment complete mortality was only reached 

 at 59('.. whereas with the five minutes treatment practically all the 

 worms were killed at 50P C. The , mperature is probably very 



nearly the minimum temperature which kills the worms, which shows 

 that the full effect of heat treatment is obtainable in live minnt 



The next three columns give the results of experiments with 

 the Domains' experimental machine. This machine consisted of an 



