220 IVAN E. WALLIN 
4, Bacillus megatherium and spores. Bacilli and spores un- 
stained, outlines difficult to see. . 
5. Unknown cocci. Preserved, but unstained. 
G. Action of moist heat on bacteria 
Various strains of bacteria were placed in vials containing 
physiological salt solution and kept in an oven at a constant 
temperature of 49°C. 
a. After thirty minutes at 49°C. 1. Human tubercle bacilli. 
Bacilli could not be demonstrated by staining. Field apparently 
contained fat globules. 
2. Bovine tubercle bacilli. Bacilli could not be demonstrated 
by staining. Field contained granular remains, stained amor- 
phous masses and apparently fat globules. 
3. Staphylococcus pyogenes aureus. Cocci could not be dem- 
onstrated by staining. Remains very minute granules. 
4, Bacillus megatherium and spores. Bacilli could not be 
demonstrated by staining. Spores coalesced. 
5. Unknown cocci. Cocci could not be demonstrated by stain- 
ing. Remains, stained amorphous masses. 
DISCUSSION 
The results obtained from these experiments demonstrate that 
bacteria may lose their staining properties when subjected to the 
action of certain chemicals ordinarily used in microscopical tech- 
nique. The degree to which the staining reactions were affécted 
varied with the different chemicals and also with the strain of 
bacteria. 
In many cases the bacteria retained their form, but were 
unstained, and in other experiments the bacteria were fragmented. 
In the cases where the organisms could not be seen they ap- 
parently had been dissolved or fragmented. In the majority of 
experiments where the remains on the slide were granular and 
fragmented these remains were stained. The possibility suggests 
itself that mitochondria may behave in the same way and that 
some of the irregularly shaped mitochondria sometimes observed 
may be the fragments resulting from chemical action. 
