308 



in. Centrifuge. 



This consist.s of a wooden frame GO cm. long, 55 cm. wide, and vary- 

 ing in height from 30 cm. at the lowest point at A to 60 cm. at B. Fig. 

 3 gives a view of the apparatus as seen in vertical median longitudinal 



Fis. 3. 



section. This apparatus in part resembles the centrifuge figured by Det- 

 mer, but is larger and possesses many improvements over his apparatus 

 (Detmer Pflanzenphysiologie Zweite Auflage, 1895, p. 384). The machinery 

 consists of a brass shaft 70 cm. long, in two sections C and D, which at 

 E may be connected or disconnected by tightening or loosening the clamp 

 E'' by screws F F'. In this way part or all of the machinery may be 

 run at one time, which is often desirable. The ends of the shaft are held 

 by a support G near E, and on D is a cone-pulley H by means of Avhich 

 it may be driven by other power if so desired, or from which power may 

 be taken for otlier purposes if tlie cone-pulley I on C is in use. On the 

 end of the shaft D is a bevel-gear arrangement so that motion is trans- 

 mitted at right angles to D in the shaft in J which carries the disk L. 

 By exchanging the position of M and N a faster motion of L may be ob- 

 tained, with no increase in the speed of D. Again by using a still larger 

 cog at N and a smaller cog at M, any speed desired may be had. By a 

 vice versa arrangement of cogs a very slow rotation of L is effected. 

 It is of course to be understood that by varying the size of the cogs M 



