METHODS FOR THE MICROSCOPIC STUDY OF BACTERIA 187 



(e) Expose to ether vapor to fix section to slide. 

 (/) Stain with anilin oil methyl violet for five to twenty minutes. 

 (g) Remove excess stain with normal salt solution. 

 (h) Gram-iodin solution for one minute. 

 (i) Remove excess iodin with water. 



( j) Remove moisture as thoroughly as possible with filter paper. 

 (k) Dehydrate in several changes of anilin oil. 

 (/) Clear with several changes of xylol. 

 (m) Mount in neutral xylol balsam. 



Staining Tubercle Bacilli in Tissues. (a) Paraffin sections are 

 covered with carbol-fuchsin and steamed gently for five minutes. 



(b) The excess stain is removed with water. 



(c) Decolorize and counterstain with Gabbet methylene-blue sul- 

 phuric acid stain about one minute. 



(d) Remove excess of stain and acid with water. 



(e) Dehydrate with absolute alcohol. 

 (/) Clear section in xylol. 



(g) Mount in xylol balsam. 



Staining Actinomyces in Tissues Mallory Method. 1 (a) Stain 

 paraffin sections with saturated aqueous eosin for ten minutes. 

 (6) Remove excess stain with water. 



(c) Stain with anilin oil methyl violet for two to five minutes. 



(d) Remove excess stain with normal salt solution. 



(e) Remove excess water with filter paper. 

 (/) Clear in anilin oil. 



(g) Remove anilin oil with several changes of xylol. 



(h) Mount in neutral xylol balsam. 



The clubs stain pink, the filaments blue. 



IV. Methods and Media for the Cultivation of Bacteria. One of 

 the most important procedures in bacteriology is the preparation 

 of nutritive media in which the morphology, chemistry, and cultural 

 characteristics of the organism may be studied; furthermore, it is 

 possible by cultural methods to separate one type of bacterium in 

 pure culture from associated organisms, and to study its reactions 

 apart from all contaminating microorganisms. The technic of isolat- 

 ing and cultivating bacteria is exacting at every step of the process, 

 from the preparation of glassware to the selection of suitable nutritive 

 media, and their preparation requires not only scrupulous cleanliness; 

 it necessitates a most rigorous maintenance of sterility. 



1 Loc. cit., p. 433. 



