ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 



269 



anatomical structure. It was constructed in 1876, and has since been 

 in constant use for ordinary observations and photomicrography. 



Fig. 40. 



The application of a mechanical stage nearly 12 in. square, per- 

 mitting 4 in. of motion in all directions from the optic axis, necessitated 

 sundry modifications of design and construction from the usual models 



Fig. 41. 



in order to secure the utmost freedom for the various manipulations, to- 

 gether with the accuracy of movement required in using high powers. 



