38 SYMBIONTICISM AND THE ORIGIN OF SPECIES 



such numbers in so short a time. Again the constancy of 

 the organisms in different experiments is against the prob- 

 abiUty of contamination from the air. These facts, appar- 

 ently, admit of no other interpretation than that mitochondria 

 are living organisms, symhiotically combined with the cells of 

 plants and animals. 



PLATE II 



All illustrations are camera lucida drawings made at the same 

 magnification. 



Fia. 1. Organisms developed on surface of culture medium when new- 

 born rabbit liver was planted in a rabbit liver medium (D), pH 6.6. 



Fig. 2. Organisms grown from new-born rabbit liver in rabbit liver 

 medium (D), pH 7.4. 



Fig. 3. Organisms grown from new-born rabbit liver in rabbit liver 

 medium (D), pH 8.2. 



Fig. 4. Organisms grown from new-born rabbit liver in rabbit liver urea 

 medium (D), pH 7.4. 



Fig. 5. Subculture of organisms of figure 2 into a different rabbit liver 

 medium (C), pH 6.0. 



Fig. 6. Organisms grown from new-born rabbit fat in nutrient agar 

 tryptophane medium, pH 7.5. 



Fig. 7. Subculture of clouded medium into rabbit liver urea medium 

 (D), pH 8.2. 



Fig. 8. Subculture of clouded medium into nutrient agar tryptophane 

 medium; pH 7.5. 



Fig. 9. Subculture of clouded medium into nutrient agar urea medium, 

 pH 6.5. 



Fig. 10. Subculture of clouded medium into rabbit liver medium (F), 

 pH 7.5. 



Fig. 11. Subculture of an upgrowth into nutrient agar, pH 6.5. 



Fig. 12. Subculture of an upgrowth into rabbit liver medium (F), pH 

 7.5. 



Fig. 13. Normal liver of a three-week-old rabbit (K*). 



Fig. 14. Liver of rabbit K* after 2 hours incubation in rabbit liver urea 

 medium (F), pH 7.5. 



Fig. 15. Liver of rabbit K* after 4 hours incubation in rabbit liver urea 

 medium (F), pH 7.5. 



Fig. 16. Liver of rabbit K* after 6 hours incubation in rabbit liver urea 

 medium (F), pH 7.5. 



Fig. 17. Liver of rabbit K* after 8 hours incubation in rabbit liver urea 

 medium (F), pH 7.5. 



Fig. 18. Liver of rabbit Sc. after 6 hours incubation in rabbit liver urea 

 medium (F), pH 7.5. 



