1-0'J Journal of Applied Microscopy 



Wash for an hour in running water and dry. With this plate, heat may be 

 used to hasten the evaporation of the water from the gelatin. 



The time limits here set are. of course, operative only under the conditions 

 given. Increased light, either from greater transparencv of the ground glass. 

 enlarged aperture of substage diaphragm, or decreased magnification will mate- 

 rially shorten the time of exposure. It is possible, also to decrease considerably 

 the exposure by employing a rapid plate instead of the slow one recommended. 

 Some circumstances may justify this use, but ordinarily, the slow emulsion will 

 give the better results. 



Finally, one other suggestion may prove of advantage. Excessive contrasts 

 may exist in the object itself, and it is desirable to reduce these. This may be 

 accomplished by an over exposure producing a flat negative which may be made 

 printable by subsequent intensification. This will give general detail even when 

 the object is dark. Variations in density and detail, within more or less narrow 

 limits, may also be secured by choosing printing papers of different kinds ; this 

 choice is particularly important when prints are made for micro-mechanical repro- 

 duction, since the balance of light and shade is not equally preserved by the 

 various papers under these circumstances. C. E. McClung. 



University of Kansas. 



A LABORATORY CAMERA STAND. 



Photographic reproductions ot material for illustrating Experiment Station 

 and other literature have become important aids in technical work and have been 

 used with more or less success — frequently the latter. The ditticulty does not lie 

 in the photographic processes, but rather in carrying them out. There are cer- 

 tain lines of work in which the photographic processes are not easily employed, 

 such as illustrating microscopic insects and fungi. Even this field mav be occu- 

 pied in time. As long as botanists and entomologists depended upon the por- 

 trait photographer to prepare the negatives, the work was usuallv most disap- 

 pointing : but with the advent of plant and insect photographers, some most 

 excellent and pleasing results have been obtained. 



In his little booklet on photographing trees and rlowers. Mr. j. Horace 

 McFarland has shown some things that mav be done with simple apparatus. 

 Before seeing this pamphlet an order was let for a laboratorv stand that differs 

 greatly from the one illustrated by Mr. McFarland. and also from the one used 

 in the botanical laborator}- of the Florida Agricultural College. The one at 

 Clemson College is used for photographing diseased plants, individual plants, 

 and similar m.aterial. with no idea of using it for illustrating bouquets or pot 

 plants. 



The source of light is from a high window to the north, making the illumi- 

 nation like a skylight. 



The ST.\Nn. — The frame is made of one-inch angle-iron and holds the 

 camera post and a ."iO x oO-inch glass plate. At the lower end of the post is a 

 mirror, attached by mechanical contrivances in such manner as to allow it to be 

 raised or low^ered ; tilted forward, backward, or sidewise; brought nearer to the 

 object or drawn back from it ; or so adjusted as to throw the reflection oft" 



