272 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



MICEOSCOPY. 

 a. Instruments, Accessories, &c.* 



(1) Stands. 



Pfeffer's Botanical Microscope-t — This instrument (fig. 38) was de- 

 signed by Dr. W. Pfeffer for measuring the growth of plants, more 

 especially in cases where it would be inconvenient to make use of a 

 lever which requires a thread to be tied to the plant. 



The body-tube racks in a horizontal socket, over which is supported 



Fig. 3S. 



a spirit level, the instrument being adjusted by the three screws in the feet 

 of the tripod. The socket is attached to a fine micrometer screw, which 

 works through a screw collar on the top of the pillar; by turning this collar, 

 which is graduated and milled, the screw rises and falls, and with it the 



* This Bubdivtsion contains (1) Stands; (2) Eye-pieces and Objectives; (3) lUu- 

 niiiiating and other Apparatus ; (4) Photomicrography ; (5) Microscopical Optics 

 aud Manipulation ; (6) Miscellaneous. 



t Pfeffer's 'Pflanzenphysiologie,' Band ii. (1S81) pp. 84-5 (1 fig.). 



