rROCEEDIiN'GS OF THE THIRD ENTOMOLOGICAL MEETING 495 



to have little or no effect on the seed. At 75° the fatal temperature 

 for cotton-seed is already being approached, the germination after five 

 minutes exposure to 75° falling." 



As will be seen later, these temperature hmits have been found to^ 

 apply to seed treated by heat by other methods, now being appHed 

 commercially. 



Dry heat was in 1913 also experimented with and was found to kill 

 the worms sufficiently (100 per cent.) without injuring the germina- 

 tion of the seed. We gave a table showing temperature of the air,, 

 time required and results to worms and germination confirming our- 

 statements. However, we failed at the time to examine the extreme 

 temperature reached by the seed, and thus missed obtaining confirma- 

 tion of the immersion temperatures. 



Cold temperatures to — 6° C. were tested, but found ineffective. 

 Worms subjected to a partial vacuum were not affected. " 



Fumigation with hydrocyanic acid gas, carbon bisulphide, and 

 sulphur dioxide were tested. The first two gave good, the last only 

 partial results (carbon tetr a- chloride was tested at a later date, but gave 

 negative results). Ammonia and motor- spirit were tested, giving very 

 poor results, and tobacco smoke, giving negative results. 



Immersion of the seed in Cyllin solution 1 : 1000 for 24 hours was 

 found satisfactory, and in a proprietory insecticide called Salvatorine 

 18 : 1000 which killed both worms and seed. 



About the time when these experiments were being made, we were 

 informed that it was possible to electrocute the worms, and that this 

 method led to satisfactory results. On testing, it was found to have 

 practically no effect on the worms. 



Of the methods just mentioned the heat treatment has finally been 

 adopted as the standard, not however without the fumigation method 

 by carbon bisulphide and by hydrocyanic acid gas both having been 

 tested on a commercial scale. 



The carbon bisulphide method was tested on a large scale in a 

 machine built entirely in Egypt by Messrs. T. Cook & Sons to the order 

 of the Ministry of Agriculture. This machine was origmally erected. 

 at the Domains ginnery at Sakha, and has since been re-erected in the 

 grounds of the Ministry of Agriculture at Cairo. 



The machine consists of six vats, connected to each other and to 

 an air-pump by a series of pipes. The vats can be hermetically closed. 

 They are intended to be filled with cotton-seed, and are each of two 

 cubic metres capacity. An opening at the top allows for filling with. 



VOL. II F 



