ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 



441 



Reinke's Microscope for observing the Growth of Plants.*— J. 



Eeinke, amongst other apparatus for observing the growth of plants, 

 devised the instrument shown in fig. 56. 



A tripod D supports a hollow pillar S in which slides a second 

 pillar C E which can be raised to a height of 32 cm. from the table 

 and is fixed with a clamp screw. To the latter pillar is attached a 

 horizontal Microscope A focusing by the eye-piece and magnifying 

 about 100 times. In front of the objective B is a glass wheel R 



Fig. 56. 



6 cm. in diameter with a grooved edge which runs very easily on two 

 fine steel points let in the bent arm F G shown in the figure. A 

 mirror on a second arm H illuminates the field of view. 



A thread P passes over the groove in the wheel, the end of which 

 is attached to the plant under examination, and at the other is a weight 

 Q to keep the thread stretched. The circumference of the wheel for 

 10 cm. is graduated in half millimetres, and each millimetre is 

 numbered. In the body-tube of the Microscope is a micrometer scale 

 with 50 divisions. This is to be adjusted so that the and 50 of 



* Bot. Ztg., xxxiv. (1876), pp. 65-9, 91-5, 105-43, 145-60, 169-71 (2 pis.). 



