ON THE NATURE OF MITOCHONDRIA 207 
I. OBSERVATIONS ON MITOCHONDRIA STAINING METHODS 
APPLIED TO BACTERIA 
In the following staining methods in which a fixation preceded 
the staining, smears were made in the usual way on the slide. 
Before the smears had time to dry they were immersed in the 
fixatives of the different methods and later treated according to 
the procedure for the particular method. In a few instances 
bacteria were centrifuged, fixed en masse, embedded, and sec- 
tioned. 
The procedure in the janus green vital staining followed the 
method used by Cowdry (714) for blood cells. 
a. Bensley’s acid fuchsin methyl green method 
This method was used according to the directions given by 
Bensley (11). It was found that the time for both fixation and 
staining could be shortened considerably with excellent results, 
obviously due to the more rapid penetration in the bacterial 
smears. In a number of instances the method was altered with 
a modified Flemming’s fixation. This modified fixative consisted 
of osmic and chromic acids in the following proportions: 4 cc. 
2 per cent aqueous solution of esmic acid and 6 cc. 1 per cent 
aqueous solution of chromic acid. This modification appeared 
to give a more rapid fixation and also good staining results with 
bacterial smears. 
Besides a large number of unknown bacteria, the followmg 
strains were subjected to this method: human and bovine tubercle 
bacilli, Bacillus coli communis, Bacillus bulgaricus, Bacillus meg- 
atherium, Bacillus subtilis, Staphylococcus pyogenes aureus, 
Staphylococcus albus, and a pneumococcus. 
In every case where this method was used the bacteria were 
well stained. In the majority of cases they were sharply stained. 
b. Schridde’s modification of Altmann’s method 
This method was used only to the extent of determining a 
positive staining in a few cases. The same difficulty experienced 
in demonstrating mitochondria with this method was experienced 
