Photomicrographs and Lantern Slides 



137 



optical axis of the microscope, fit to the guideway a board of the 

 necessary thickness, and fasten the camera to this board. It is 

 absolutely necessary that the preparation to be photographed and 

 the ground glass of the camera should be perfectly parallel. The 

 board will save time in securing this parallelism. Cut through the 

 board a slot J inch wide and extending to within 6 inches of each end. 

 By this means the camera can 

 be clamped with the screw 

 used to fasten it to a tripod. 

 Also, a piece of metal or hard 

 wood may be placed over the 

 horseshoe base of the micro- 

 scope and with a bolt, pref- 

 erably one with a butterfly 

 nut, the microscope may be 

 held firmly in place. This 

 board, with the long slot, will 

 be useful in making lantern 

 slides. 



As an illummant, direct 

 sunlight, diffuse daylight, a 

 gas-mantle lamp, an acetylene 

 lamp, a Nernst lamp, an arc 

 light, or any strong light may 

 be used. Remove the mirror 

 from the microscope and allow 

 the light to come directly into the optical axis. This mirror will 

 not be needed in any photomicrographic work. 



Let us suppose that we are to make a photomicrograph of a 

 vascular bundle and that we are using a 16 mm. objective. If 

 only a part- of the bundle is shown on the ground glass, remove 

 the ocular of the microscope. If the illumination is very uneven 

 and shows a "flare spot," look at the inside of the tube of the micro- 

 scope. Probably, it was not blackened and the " flare spot' was 

 due to reflections. Obviate the difficulty by putting a piece of 

 black paper inside the tube. Any modern microscope should have 



B 



C 



FIG. 25. .4, board for photomicrographic 

 and lantern-slide work; B, end view with 

 clips to hold negative; C, side view of block to 

 be used on board when making lantern slides. 



