ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 321 



of whicli the objective is composed are placed in two tubes so that 

 they can be more or less separated, either by sliding or by rack and 

 pinion. This plan was more recently adopted by Dr. Zeiss in the 

 " adjustable objectives," described Vol. III. (1880) p. 524. The fixed 



Fig, 



mount enables Dr. Zeiss to use a small diaphragm within the tube 

 which protects the eye from the glare seen with the ordinary Briicke 

 lens. 



Fig. 74. 



The smaller disbcclmg Miciobcope of Dr. Zeiss, with which, by 

 means of an adapter, a Briicke lens can also be used (though not so 

 conveniently as with the former stand, on account of the long 

 working distance of the lens), is shown in fig. 72. 



In Klonne and Miiller's large dissecting Microscope (fig. 73), 

 with which is also used a Briicke lens, the supports for the hands are 



Ser. 2.— Vol. V. Y 



