THE BACTERIAL NATURE OF MITOCHONDRIA 29 



chondria. This organism (there is some question in regard 

 to its true bacterial nature), which is associated with the 

 disease Rocky Mountain spotted fever, has been investi- 

 gated recently by Wolbach who has taken cognizance of 

 its fragile nature. A number of related forms, spoken of 

 collectively as "Rickettsia bodies," also, are characterized 

 by their fragile nature. 



Fragihty is thus not a specific characteristic of mito- 

 chondria, but in known microorganisms it appears to be a 

 property acquired in the development of a S3Tiibiotic 

 existence. 



Thermal responses. A number of investigators have 

 found that mitochondria are apparently destroyed when 

 the tissues containing them are exposed to a temperature 

 of 48° to 50°C. for a comparatively short period. It is well 

 known that microorganisms exhibit a wide range of reactions 

 to temperature. Some organisms live constantly in hot 

 springs where the temperature is not far below the boiling 

 point; others thrive in cold regions where the temperature 

 may be far below zero. 



Experiments were made in which some ten strains of 

 bacteria were placed in vials containing physiological salt 

 solution and incubated at a temperature of 49°C. for half 

 an hour. The organisms were examined before incubation 

 to determine if the physiological salt solution affected their 

 morphology. They all appeared to be intact. After the 

 incubation, a drop from the bottom of the vial was removed 

 with a pipette, smeared on a slide and allowed to dry. A 

 celloidin fihn was then floated over the dried smear to fix 

 it on the slide. In these experiments it was found that 

 some of the strains of bacteria were apparently unaffected. 

 Other strains, however, had "dissolved" or disappeared; 

 amorphous masses, stained in some cases, were all that 

 remained of the organisms. 



These expermients failed to demonstrate any fundamental 



