22 THE A B C OF PHOTO - MICROGRAPHY 



uated in centimeters slides vertically, being 

 held at any point by a set-screw. This rod 

 carries a cone-shaped bellows by means of 

 two sleeve collars, also controlled by set-screws 

 at any desired extension, and its front is pro- 

 vided with a light-tight connection between 

 the camera and microscope. As with all work 

 emanating for the Zeiss establishment it is 

 made in the best and most careful manner. 



The upright camera by Leitz has had a 

 fairly large sale in this country, principally in 

 schools and colleges. It is well made, of 

 course, and is good of its kind ; but its cost 

 ($40) seems excessive. The fact is that a 

 horizontal camera has so many points in its 

 favor that I cannot understand how any one 

 could deliberately choose an upright type 

 when purchasing, unless he were entirely 

 ignorant of the work he was about under- 

 taking. The single point of superiority pos- 

 sessed by the upright form is found when it 

 becomes necessary to photograph objects 

 moving freely in a fluid medium, such as yeast 

 cells, etc. In these rare cases the object-slide, 

 of course, lies flat and the camera must be 

 held perpendicularly above it. A little ingen- 

 uity will always enable one to accomplish this 

 in some manner, and since an occasion for so 



