and Laboratory Methods. 



1399 



LABORATORY PHOTOGRAPHY. 



Devoted to methods and apparatus for converting an object into an illustration. 



PHOTOMICROGRAPHY. 



Introductory. 



Photomicrography, as it may be practiced to-day, is of prime importance in 

 several different kinds of work. Nothing can take its place as a means of illus- 

 tration in popular lectures. In class lectures, for review, a term's work can be 

 summarized more quickly and correctly by means of the lantern slides than in 

 any other way. It has the advantage over microscopic observation, of directing 

 everyone's attention, at the same time, to the same thing. In all our colleges 

 and universities, students of history, sociology, psychology, etc., are calling 

 for lectures on the laws of growth, on what is known about heredity, on the 

 principles of kinship, etc. — students who have neither the time nor the skill to 



Fig. I. — Four day chick, x 15. 



get the foundation facts in the laboratory. Wherever illustration in histology is 

 desirable, photomicrography has advantages that will not longer permit it to be 

 neglected. 



There is no class work that must be seen through the microscope that the 

 half-tone and the lantern slide cannot faithfully present. It is the purpose of 

 the accompanying cuts to sustain this proposition. Five of the microscopic slides 

 photographed were made by students in the regular work of the class-room. 

 The negative for Fig. 1 was made with a 70 mm. apochromatic objective without 

 eye-piece, and with a camera extension of three feet. The low-power objective 

 gives penetration, and the extension gives the necessary amplification ; by just 



