208 THE AMERICAN MONTHLY [June 



For photographing the projected image orthochro- 

 matic plates should be used. Of these I have used the 

 Cramer rapid "isochromatic" exclusively, though proba- 

 bly other makes of orthochromatic plates might be found 

 to work equally well. Certainly the "isochromatic" 

 work so well that there is no necessity for going through 

 the trouble of orthochromatizing plates one's self. 



In developing I have obtained best results with formu- 

 las in which hydrochinone alone or with some other re- 

 ducing agent is used. The following give clear negatives 

 of sufficient contrast and graduation : 



No. 1 



Water 300 



Sodium sulphite 25 



Potassium bromide 0.5 



Hydrochinone 1.5 



Methol 1.5 



No. 2 



Water.. 15 



Sodium carbonate 300 



Use equal parts of No. 1. and No. 2. 



Development should proceed slowly and should be con- 

 tinued until sufficient density is obtained. Rapid 

 development and removal from the developer before 

 sufficiently density is obtained are to be particularly 

 avoided in photomicrographic development. 



A few reproduced photomicrographs are given in 

 illustration of the methods outlined. They have been 

 selected as representing ordinary practical work with 

 different objectives and lights and with different means 

 of projection and substage attachments. 



Leprosy is said to be spreading in the Russian Baltic 

 provinces with alarming virulence. Several hundred per- 

 sons are said to be afflicted with the disease, and the Livo- 

 nian Diet has just taken measures for isolating them at 

 the cost of the State. 



