ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



699 



through ;i polariscope, H. Triepel has designed the model shown in 

 fig. 85. It consists of a rod about 4o cm. high, on a firm foot. Four 

 pairs of cardboard sheets fitting into tubes are slipped over the rod, and 

 are thus easily adjustable in any required vertical positions. In each of 

 the two central pairs the cards arc at right angles. The whole arrange- 



Arralysator. 



Hauptschnltt. 



Sinachsigr negahv doppeUbrichentl. 

 Ausserordentticher Strahl 



Fig. 85. 



ment illustrates the ray as it passes successively through polarizator, 

 selenite, object, and analyzer. The optical axis is supposed to be vertical, 

 and the axis of the nicol prism inclined to it at 22°. Suitable informa- 

 tion is recorded on the sheets. 



Leitz Liliput Arc-lamp.* — This auxiliary is intended for photo- 

 micrograph^ use, and is illustrated above in fig. 63, p. 541. It pro- 



Leitz, Catalogue 43 G, Photomicrographic Apparatus, p. 9. 



