and Laboratory Methods. 



1655 



LABORATORY PHOTOGRAPHY. 



Devoted to Methods and Apparatus for Converting an Object into an Illustration. 



Fig. 1. — Aecidium fraxini xl2. 



PHOTOGRAPHLNG UREDINEAE WITH THE MICROSCOPE. 



The apparatus used consists of a small Zeiss microscope, projecting ocular 



No, 2, condenser of 1.00 N. A., biconvex lens on adjustable stand, 3 in. B. & L. 



objective, one-sixth Spencer oil immersion objective, made specially for use with 



orthochromatic plates, and an acetylene lamp. 



When using the one-sixth objective the 

 lamp is placed about four feet from the 

 stage of the microscope, and the condenser 

 accurately centered by taking a l;!4-inch 

 objective and projection ocular, and focus- 

 ing on the edge of the iris diaphragm. 

 The biconvex lens is then placed between 

 the light and microscope so as to bring the 

 image of the flame a few inches from the 

 substage condenser, and centered by focus- 

 ing on the image of the rim. The lamp is 

 then adjusted until, on looking down the 

 tube, the image of the flame is in the 

 center of the image of the biconvex lens. 

 The slide to be photographed is placed 



on the stage, a piece of ground glass placed so that the image of the flame from 



the biconvex lens is sharply focused upon it (moving the ground glass into the 



focus and not disturbing the 



lens), and the substage con- 

 denser raised or lowered until 



a shirp image of the flame is 



seen on the object, and the 



glass is then removed. 



Until recently I supposed 



that a projection eyepiece cut 



off all reflections and useless 



rays, but I find that much 



finer negatives can be made by 



using an iris diaphragm be- 

 tween the objective and tube 



of the microscope and closing 



the opening as far as possible 



without showing in the field of \^fc. ' 



view, and the illustrations with ^"^--^^ 



this article were all made with Fig. 2. — Puccinia amphigena x250. 



