30 



The Growth of Seedlings in Wind. 



the seeds was maintained day and night, the whole being arranged conve- 

 niently over a sink, so that the waste water ran away. The wind was made 

 to blow out through the jar and scatter the water spray along the seeds. 

 Where the water entered the temperature averaged about 24-27° C. At 

 the end of the wick near the opening of the jar the temperature averaged 

 about 18° C, which was the average temperature of the control. Fig. 3, A, 

 shows the still air, and B the wind-exposed seedlings. The latter shows a 

 growth bent and twisted, but about two-thirds as long, when straightened out, 

 as the control. Analysis showed in this case : — 





Wind-exposed seedlings. 



Still-air seedlings. 





20 mm. 

 "6455 grm. 

 8 "66 per cent. 

 91 -34 



30 mm. 

 -968 grm. 

 8 "2 per cent. 

 91 -8 „ 



A difference in size rather than in percentages of water and solid is 

 noticeable. The wind-swept seedlings in all the experiments grew no root 

 hairs, while these were abundant on the controls. 



Experiment IX. — Fig. 4 shows the result of growing cress seeds in a hot 

 room kept continuously at 37*5° C. The seeds grown in the wind were kept 

 wet by water which dripped out from a glass tube, the end of the tube lying 

 on the wick close to where the growth is seen to be best. At the left end 

 of the wick the growth is nil, although the wick and the under surface 

 of the seeds were wet. The drying of the upper surface of the seeds was 

 sufficient to stop growth. In the intermediate part the growth was better 

 with the increasing wetness of the seeds. The control was placed so that 

 the water from the wick in the wind tunnel dripped upon it. This dropping 

 rain especially favoured growth in the hot room. It was greater than that 

 shown in Fig. 3, A. Seeds kept just totally immersed did not grow. The 

 amount of moisture the seeds receive is obviously of very great importance. 



Experiment X. — Fig. 5 shows the growth in the hot room in wind, B, and 

 out of the wind. A, both wicks being irrigated by falling drops of water so as 

 to make the conditions of water supply as exactly comparable as possible. 

 The growth of the seeds in the wind is still behind that of the control. The 

 approximate average length of five seedlings was 2-5 cm. in the wind and 

 3'0 cm. in the control. The weight of 26 seedlings minus the seeds was 

 0'315 grm. in the control and 0"284 grm. in the wind. The percentage of 

 solids was 13*8 and 17'2 per cent, respectively. 



The temperature of the wet wick was 29° in the control and 26° in the 



