EFFECTS PRODUCED BY PINK BOLLWORM 'ON THE YIELD OF COTTON SEED. 289 



Table VI. Showing the Fluctuation of Weight of Cotton Seed under Extreme 



Conditions. 



Days of 



Weight of seed 



Days of 



Weight of seed 



exposure to 



desiccated over 



exposure to 



kept in moist 



experiment. 



sulphuric acid. 



experiment. 



chamber. 







10-020 grs. 







10-250 



1 



9-797 „ 



1 



10-750 



2 



9-735 , 





2 



10-812 



3 



9-692 . 





3 



11-112 



4 



9-672 , 





4 



11-280 



5 



9-670 , 





5 



11-350 



7 



*9-865 , 





7 



11-785 



8 



9 739 , 





8 



*10-470 



9 



9-685 , 





9 



*10-450 



14 



9-535 , 





14 



11-648 



16 



9-435 , 





16 



11-750 



17 



9422 , 





17 



12-470 



* The lid of the desiccator was found to have slid open. 



The first record extended over a period of three days. Unfortunately in two 

 places the weight record is broken. This is due to the weight of the seed having 

 increased so much as to make the beam of the balance rest on its support. On 

 the graph the weight curve has been redrawn, as for two grammes of seed ; as 

 ten grammes were actually used, the vertical component of the curve has been 

 reduced five times. It will be seen that the seed-weight curve followed the 

 humidity curve very closely, but with a lag of about two or three hours. Minor 

 changes of humidity were not recorded by the seed. The actual variation in 

 weight of two grammes of seed was found to be about 4 mg. per 10 degrees of 



XII 2 4 6 8 I0M T 2 4 6S loXHs 4 6 8 loM T a 468 10 Xlla 468 loM T 2 468 10 XII 



- _ 



TM 



s 



rk= 



ft 



k 





1 







— = 



— > — 



* 



■■* 



70 

 60 

 50 

 40 



Fig. 1. Fluctuations in humidity (solid line) and simultaneous 

 fluctuations in weight of two grammes of cotton -seed (broken line). 



humidity, when the humidity itself varied from about 46 to 50 degrees. A rise 

 in temperature is accompanied by fall in weight. The quick, short variations 

 in the humidity record at 24 hours were due to the floor of the dark-room having 

 been watered in the hope of inducing fluctuations in the records. As will be seen, 

 the influence of the evaporation of water in the room was quite small as compared 

 with the general climatic changes which made themselves noticed. It was the 

 lag that made it previously so difficult to obtain agreement between the changes 

 in the weight of the seed and the fluctuations of the hygrometer. We shall have 

 to return to this subject later on when discussing the percentage of lint. The 

 (C541) b 



