1899] MICROSCOPICAL JOURNAL. 83 



though they were evident in quantity when the prepara- 

 tion was counterstained with methylene blue. The tu- 

 bercle bacilli still retained their characteristic red color 

 and appearance. 



III. Sections of a Tuberculous Lung. — Sections from 

 the lung of a man who died of bronchial tuberculosis 

 were stained from five to ten minutes in a concentrated 

 eighty-per-cent alcoholic solution of sudan iii washed 

 from five to ten minutes in several changes of seventy- 

 per-cent alcohol, counterstained with methylene blue, 

 dehydrated with absolute alcohol, cleared with clove oil, 

 and mounted in Canada balsam. In this preparation the 

 tubercle bacilli were stained red and could be distinctly 

 seen lying in the tissue. The material from which the 

 sections were made was prepared in the following way : 

 Pieces of the lung were placed in absolute alcohol and al- 

 lowed to remain for a week, then changed into a fresh lot 

 of alcohol, and from that passed through alcohol and 

 ether into celloidin in the usual way. The sections after- 

 staining were also dehydrated with alcohol, but in spite 

 of this fact the tubercle bacilli were well stained by 

 sudan iii. It is thus evident that their staining proper- 

 ties are not influenced by the dehydrating action of the 

 alcohol. This differs from the method prescribed by 

 Daddi in staining sections for fat, as Tie recommends that 

 care should be taken not to dehydrate with alcohol or 

 clear with clove oil. Possibly the fatty material in the 

 bodies of the tubercle bacilli is not as soluble as that de- 

 posited in the tissues. It should be noted, however, that 

 preparations stained with sudan iii and mounted in Canada 

 balsam did not retain a bright color after a month's time. 



To demonstrate further that sudan iii is apparently a 

 selective stain for tubercle bacilli, I endeavored to stain 

 the numerous varieties of bacteria found in decomposing 

 sputa, pure cultures of hog cholera, glanders, typhoid, 

 anthrax, symptomatic anthrax, diphtheria, and prorligiosus 



