BACTERIOLOGICAL TECHNIC 45 



Kuhne's methylene blue 



Methylene blue 1.5 grams 



Absolute alcohol 10 c.c. 



Carbolic acid solution (5 per cent) . . 100 c.c. 



Carbolic gentian violet (Nicolle) 



Gentian violet (sat. alcoh. sol.) 10 c.c. 



Carbolic acid i gram 



Water 90 c.c. 



Pappenheim's Stain 



Sat. aqueous solution of methyl green 3-4 parts 

 Sat. aqueous solution of pyronin i-i . 5 parts 



Mix previous to staining. Apply for 20 seconds. 

 The mixture is dependable for a few weeks only. 



SECTION 7 



THE MICROSCOPE 



(Fig. 19) 



The compound microscope is a necessary adjunct 

 to any kind of bacteriological work. For this work 

 three objectives (Leitz No. 3, No. 6, or No. 7 and T \ oil 

 immersion, Zeiss No. A or No. AA, No. D or No. DD, 

 and 2 mm. oil immersion) and two oculars (Nos. 2 and 

 4) are indispensable. For the intelligent manipula- 

 tion of the microscope it is useful to understand the 

 underlying optical principles, which may be studied 

 from special works on the subject. 



References 



S. H. Gage, The Microscope. 



Carpenter and Dallinger, The Microscope and Its Revelations. 



For use in the laboratory it will be sufficient to call 

 attention to some of the most important points to be 

 observed. 



