THE BACTERIAL NATURE OF MITOCHONDRIA 35 



of the earlier experiments. A number of specimens were 

 subcultured into the new media. In a large number of the 

 subculture experiments, the coccoid bodies of the clouded 

 media developed definite surface growths. Deep clouded 

 growths that were several weeks old did not develop into 

 surface growths so readily as did younger cultures. These 

 results in subculturing the deep clouded growths removed 

 the last vestige of doubt concerning the bacterial nature of 

 the coccoid bodies. 



There is no occasion to confuse the coccoid bodies ob- 

 served in these experiments with the "artificial bacteria" 

 produced by Fischer ('99), Lowschin ('13) and others. 

 Precipitation of colloids may be produced in solutions by 

 various methods, the precipitate assmning various forms 

 and characteristics. Some of these may have a morphologi- 

 cal resemblance to the coccoid bodies and to bacteria. 

 Evidence is lacking, however, that the precipitates can be 

 subcultured upon the surface of sohd media and caused to 

 multiply, properties shown to be possessed by the coccoid 

 bodies and known to be characteristic of most bacteria. 



A large number of culture experiments were then made, 

 in which liver tissues from fetal, new-born and adult animals 

 were planted in the tryptophane and urea media. When 

 tissues from the fetus and new-born were used, surface 

 growths developed in practically all cases with either media. 

 In a few experiments in which adult tissue was used surface 

 growth appeared in nearly all of the tryptophane media 

 tubes, but in none of those containing urea. 



The morphologic nature of the organisms that developed 

 in the culture experiments was puzzhng. The constancy 

 with which surface growths appeared, and the precautions 

 used in the experiments appeared to rule out contamination, 

 nevertheless, the morphology of the organisms seemed to 

 point to it. The mitochondria of the liver cells are mostly 

 globular bodies. A few ovoid forms are usually seen in the 



