ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



243 



The movable stage is also controlled from the ground glass 6 ft. 

 away by brass rods with milled heads and cord and pulley attachment, 

 and the stage is supported against the strain of these by an adjustable 

 brass pillar G. The stage can thus easily and quickly be searched over 

 a space f- in. square. The coarse adjustment of the Microscope is 

 similarly controlled. 



The adjustable pillar B, under the Microscope, to offset the pull of 

 the cord on the fine adjustment screw, was specially added by Mr. Dennis, 

 and seems to suggest that the Zeiss model in its original form was not 

 sufficiently steady for very high powers. Mr. Dennis has also added 

 the controlling arrangements of the coarse adjustment, the stage, the 

 adjustable pillars under the Microscope bench, and the adjustable pillar 

 under the stage. He has, moreover, placed scales on both the camera 

 table and the optical bench, so that all parts of the apparatus can be 

 ■ quickly brought into any desired relationship. 



Fig. 52. 



Colour Photomicrography.* — F. L. Kichardson makes some con- 

 tributions to our knowledge of this subject. He considers that, of tho 

 plates now in use, the orthochromatic approaches most nearly the ideal 

 colour plate, but that this is not perfectly satisfactory, as it does not 

 give sufficient contrast. He therefore undertook some investigations to 

 determine the relative merit of various photographic plates. The 

 apparatus, as illustrated in fig. 52, consisted of a direct vision spectro- 

 scope, so mounted in the front board of an ordinary camera (with lenses 

 removed) that the spectrum, when projected on the plate, would come in 

 the centre horizontally and at the top of the plate. The back of the 

 camera was constructed in such a manner as to allow of its being moved 



* Joum. Boston Soc. Med. Sci., 

 pp. 1489-92 (3 figs.). 



pp. 460-4;] and Joum. App. Micr., 1901, 



E 2 



