208 IVAN E. WALLIN 
with bacteria. Bacillus bulgaricus, Bacillus coli, and Staphylo- 
coccus pyogenes aureus were definitely stained by this method. 
c. Benda’s crystal violet method 
A fairly large number of known and unknown bacteria were 
subjected to this method. - Bacteria responded to this method 
just as mitochondria do. It gave the sharpest differentiation of 
bacteria obtained in any case where mitochondrial methods were 
used. Compared with Gram’s stain, for example, on sputum 
smears, it gave a sharper differentiation. Here, also, it was 
found that the time for fixation and mordanting may be reduced 
considerably. 
d. Copper hematoxylin method 
This method was applied to only a few strains of bacteria. In 
some cases the staining of the bacteria was quite faint. This was 
particularly true after fixation with Zenker and the formalin- 
Mueller used with the Altmann-Schridde method. After Bens- 
ley’s and the modified Flemming fixations the bacteria were 
stained very sharply by the copper hematoxylin method. 
e. Janus green vital staining method 
This method was used as prescribed by Cowdry (14) in a 
1:10,000 dilution in physiological salt solution. The dye was 
first tested by applying it to lymphocytes from a lymph node of 
the rabbit. It was found to stain the mitochondria of the 
lymphocytes as described by Cowdry. 
The following results will serve to indicate the staining re- 
action on bacteria: 
1. Human bacillus tuberculosis, viable strain. The bacilli 
stained rather faintly, the granular forms were easily recognized 
on account of the more intense staining of the granules. Ob- 
served ten hours after the preparation was made, the bacilli ap- 
peared to be stained slightly deeper. 
2. Bovine bacillus tuberculosis, viable strain. The bacilli 
stained perhaps a little fainter than the human strain. Observed 
