ARRANGEMENT OF APPARATUS. 135 



for the production of the Negative, from which the 

 print of the Bacillus Anthracis in the frontispiece was 

 produced, may prove of use as an illustration. 



Apparatus, horizontal, placed in recess of dark 

 room, camera not attached to microscope. 



1. Section of lung containing Bacilli Anthracis pre- 

 pared by Ehrlich's method. 



2. Objective one-eighth imm., corrected to thirty- 

 five for cover glass. 



3. Condenser single French front, with dry eight 

 top, one-sixteenth of an inch from object. Aperture of 

 sliding diaphragm as close to the back of condenser 

 as possible, and covering half the diameter of the 

 field when brought into focus with one-fourth 

 objective. 



4. Blue glass near condenser. 



5. Bull's-eye eleven inches from stage of micro- 

 scope. 



6. Lamp one inch from bull's eye, parafin and edge 

 of wick. 



7. Ground glass of camera twenty-four inches 

 from object. 



8. Usual focus. 



9. Glycerine and water the immersion fluid. 



10. Gelatine plate, twenty times collodion. 



11. Exposure three minutes. 



12. Ferrous oxalate developer; two drops of fifty 

 per cent, bromide solution added to one ounce. 



13. Result shown in photo. 



