

EFFECTS PRODUCED BY PINK BOLL WORM ON THE YIELD OF COTTON SEED. 317 



The machines were run to give 55° C. temperature to the seed by the time it 

 was discharged with the sacks, this being the lowest safe temperature to control 

 Geleehia, although considerably under the maximum safe temperature for seed 

 germination. 



Table XXV shows the results of the germination tests. Of the 501 samples 

 tested only 5 had been damaged to a significant extent in their germination, but 

 the damage in these five cases was not serious, — over 70 per cent, germinating. 

 Little can be said definitely about the destruction of the larvae, as the samples 

 were singularly free from them, 3 or 4 on an average being found per kilogram of 

 seed. As far as could be seen under these conditions the machines were working 

 efficiently in this respect also. . 



Cotton-seed is germinated in the Entomological Section under the following 

 conditions, which have been found to give very regular results. Germination 

 takes place in the germination room, which has a capacity of about 27 cubic metres. 

 This room is kept at a constant temperature of 30° C. by a small hot-water radiator 

 heated by gas, the gas-supply being regulated by a Hearson's capsule, which operates 

 a locally-made regulating valve. The whole of the heating apparatus and the 

 regulator are inside the room. Double doors, enclosing an air-lock, prevent undue 

 changes of temperature when workers enter or leave the room. The window is 

 double, enclosing an air-space. The ceiling is also double. Combustion gases are 

 led out from the burner of the radiator by a flue. The construction of this room 

 has been found so satisfactory as regards temperature control, that thermograph 

 records running over several weeks show fluctuations of only half a degree above 

 or below the desired temperature. 



The seed is germinated in samples of 50 grammes each, equivalent to about 

 500 seeds. The standard deviation for samples of this size has been found to be 

 4 per cent. Worm-eaten seeds are not counted, all other seeds are recorded after 

 48 hours as germinated or failed. The germination actually takes place in glazed 

 earthenware dishes, 20 cm. across by 7 cm. deep. The seed is placed in a single 

 layer on a circle of felt which covers the bottom of the dish, and covered by a 

 second sheet of felt, 100 cc. of water of 30° C. being given to start the germination ; 

 after 24 hours more water of the same temperature is given to each sample. The 

 felt is washed in copper sulphate solution after each use, and then dried. The 

 room is calculated to take up to 4,000 dishes at a time, if all the shelf space is occupied. 



This system of germination has given perfect satisfaction. Formerly when 

 working with Petri dishes in Hearson incubators a very large number of putrefying 

 samples were obtained, which had to be repeated ; under the present system no 

 putrefying sample has been observed, and it has not been necessary to repeat 

 germinations on this account. The few " repeat " samples made, due to extreme 

 figures being obtained, have proved on retesting to be significant. 



During the early part of 1918, 2,000 ardebs* of seed were fumigated at the State 

 Domains ginnery at Sakha, under the supervision of Mr. Storey, Entomologist 

 in the Ministry of Agriculture. These samples are mentioned here, as they were 

 treated at higher temperatures than the seed just discussed, being destined for 



* About 11,000 bushels, or 235 tons. 



