ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



427 



phragms fit into a fixed tubing below the stage. The diaphragm-tube 

 slides in /, and the milled heads d serve to remove the plate when it is 



Fig. 76. 



required to change the diaphragms. In some cases centering arrange- 

 ments have been adapted, M. Nachet uses, in place of a sliding plate, 



Fig. 77. 



a movable arm which swings away from the stage in changing the 

 diaphragms. 



Pinkernelle's Apparatus for the Examination of Fluids.* — 

 W. Pinkernelle's apparatus is shown in fig. 78. It consists essen- 



FiG. 78. 



tially of a glass plate a, in which is a channel closed at both ends by 

 taps d, and having two indiarubber pipes, of which one dips into a 



* Specification of German Patent, 1881, No. 18,071, and explanations issued 

 by the author. 



