310 



at any aii.iile and at lapid speeds by nsiiiu- clamiis to hold them in posi- 

 tion. 



As stated by Detmer. seedlings of the pi'oper size when fastened on 

 Q and rotated rapidly cui-ve outwards. I have noticed a curving against 

 the direction of motion in seedlings subjected by a stronger centrifugal 

 machine Than this exerting 4.400 gravities. 



At U (Fig. 3) is another similarly arranged disk in case it is desired 

 to run two at once at different angles. Here, however, the power is trans- 

 mitted by a belt and cone pulleys, liy means of which different speeds may 

 be obtained. U may also be inclined at an angle by loosening or 

 tightening V. At X. X' and Y the shaft is supported in journals. At W 

 is a water wheel .30 cm. in diameter, and b:, using a very strong stream of 

 water Z. a very high speed and ample power for the experiments here 

 mentioned may be developed. Naturally the speed and ix>wer cau be 

 easily controlled by the force of the stream of water. By means of the 

 cone-pulleys the machine may be driven by motor or other power. 



IV. Apparatus for Growing Plants in Different Colored Lights. 



This consists of a wooden box made perfectly tight to prevent the 

 light from entering except at H, Fig. G. It is 40 cm. long, 25 cm. wide and 

 2.5 cm. deep. Of course it is often advisable to use larger sizes of boxes, 

 but the one here mentioned will serve as an illustration. The inside 

 of the box is painted black and is provided with a base for holding 



Fig. 5. 



flower pots in any position. Each side of the box is provided with a door 

 A. Fig. 5. which by means of the clamps B and B^ may be removed so 

 that the plant inside may be adjusted in the desired position, as regards 

 the light entering at C or D, and measurements taken. The ends of the 

 box are in the form of caps E (Fig. 5) which lap over the end at F so 

 tightly that no light can enter. 



Fig. G shows an end view of one of the caps E. In this figure 

 there will be noticed a circular opening H. 15 cm. in diameter in the 



