628 
i 
PIERRE A. FISH. 
naturally presented itself that the neutral red solution might be 
incorporated with the culture media and the reaction of the dif¬ 
ferent bacteria observed directly during their growth. In the 
experiments which followed a number of micro-organisms were 
utilized among which were the following : bacillus cholerse suis. 
Proteus vulgaris and mirabilis, bacillus of diphtheria, bacillus 
fluorescens liquefaciens ; bacillus anthracis ; comma bacillus ; 
bacillus typhosus ; bacillus acidi lactici ; staphylococcus pyo¬ 
genes aureus and a yellow sarcina. 
The report of the results is purposely crude and generalized. 
A few certain well known and representative forms carefully 
tested with the various media under different conditions would 
do much towards elucidating the possession or absence of specific 
chemical reducing powers. 
In the preparation of the cultures a | per cent, solution of 
the neutral red salt was used. This was thoroughly sterilized, 
and then with a sterilized pipette ten drops of the “ red ” was 
added to the already sterilized media (bouillon, agar, or 
gelatin). The proportion being approximately io drops of the 
I per cent, solution of the red to about 8 cc. of the media. The 
resulting mixture was a bright garnet red color. Besides the 
ordinary tube and plate cultures, fermentation tubes containing* 
glucose, saccharose and lactose were utilized. As in the case of the 
others, the neutral red was added to the already sterilized media ; 
but on account of the admission of more or less air when the red 
and media were mixed, the fermentation tubes were again 
heated in the sterilizer and the bubble of air in the closed tube 
tilted out so that the reducing properties of the mixture might 
not be interfered with. 
1 he results obtained, with the various media employed and 
the action of the different micro-organisms upon them, may be 
briefly summarized into two general classes of phenomena: 
1. Those organisms which change the garnet red media to a 
fluorescent and then to an ultimate brown color. 
2. Those which do not cause fluorescence nor change the red 
color except to deepen it. 
