ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



497 



primary necessity that the camera and the Microscope shouhl not 

 be in direct contact but united only by a cloth connection. The 

 Microscope-tube may be either vertical or horizontal, but the latter 

 is the position which insures the greatest stability and facilitates 

 manipulation ; it is true that this involves some difficulty in photo- 

 graphing an uncovered preparation which is liable to slip when the 

 Microscope is horizontal, but in practice it is generally easy to fix 

 the section to the object-carrier with a few drops of paraffin. 



The Microscope and camera adopted by M. Viallanes are shown 

 in figs. 82 and 83. The latter is a sliding collapsible camera similar to 

 that used by photographers. In the front of the camera is a large 

 hole to receive the eye-piece end of the Microscope, while at the 



Fig. 83. 



back are the usual arrangements for receiving in succession the ground 

 glass for focusing, and the sensitive plate. The Microscope is fixed 

 upon the base which carries the camera slide, and in such a position 

 that the eye-piece end of the tube enters the circular hole in the 

 front of the camera, the connection being made by a metallic washer 

 faced on the inside with velvet to prevent the entrance of any external 

 light. A stop insures the tube being brought into a strictly horizontal 

 position. 



On the means of obtaining as large a field as possible, the author 

 says, " The modification required in the Microscope in order that as 

 large an image as possible may be projected upon the sensitive plate, 

 is easily efiected ; it is only necessary to increase the diameter of the 

 tube, and this has been done in our photographic Microscope. The 

 instrument with the tube thus enlarged can be employed just as well 



