ON THE NATURE OF MITOCHONDRIA 220 
The visibility of unstained bacteria varies with the difference 
in refraction of the bacteria and the surrounding medium. In 
those cases where the bacteria could not be seen the granular 
remains indicated the destruction of the organism. Unstained 
bacteria lodged in the cytoplasm of tissue cells cannot be dis- 
tinguished easily and in some cases they are not visible. It is 
generally supposed that mitochondria are dissolved by the action 
of certain chemicals. It is possible that in many cases where 
they cannot be demonstrated by staining their form has been 
retained, but unstained and consequently not readily observed. 
Bacteria apparently respond to heat in the same way that 
mitochondria do. The end-product from the action of heat was 
not the same for all the strains of bacteria that were used for this 
experiment. In some cases the remains were granular, in others 
they were amorphous. The amorphous material apparently 
represented the residuum of a solution after evaporation. 
Cowdry (18, p. 68) has noted the presence in some secreting 
cells of mitochondria with ‘bleb-like’ swellings and in egg cells 
of ‘dumb-bell-shaped’ mitochondria. The action of 1 per cent 
acetic acid on Bacillus megatherium is significant in this connec- 
tion. The imitation of such ‘bleb-like’ and ‘dumb-bell-shaped’ 
mitochondria by bacteria as the result of chemical action sug- 
gests the possibility that mitochondria of these types may be 
due to the action of the chemicals used in fixation. 
CONCLUSIONS 
The results obtained in subjecting bacteria to mitochondrial 
staining methods and to the chemicals that have been utilized 
to determine the chemical nature of mitochondria appear to 
demonstrate that these methods are not specific for mitochondria, 
but have a similar reaction on bacteria. To the degree that these 
staining methods and chemical reactions are not specific, bacteria 
and mitochondria have a similar chemical constitution. 
