ARRANGEMENT OF APPARATUS, ETC. J 23 



trance of actinic light. The subsequent manipula- 

 tions are identical with those already described. 



The following notes of the manipulations employed 

 for the production of the Negative, from which the 

 print of the Bacillus Authacis 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 Anthacis 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 inch from object. Aperture of slid- 

 ing 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 bulls eye paraffin and edge 

 of wick. 



7. Ground glass of camera twenty-four inches 

 from object. 



8. Usual focuss. 



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 

 p. c. bromide solution added to one ounce. 



13. Result shown in photo. 



