50 SYMBIONTICISM AND THE ORIGIN OF SPECIES 



J. Terrill Scott ('26), working in this laboratory, has 

 studied the responses of mitochondria to variations in the 

 hydrogen-ion concentration. When hver tissues were in- 

 cubated in physiological saline solutions of different pH 

 values for short periods of time, there was a variation in 

 the behavior of the mitochondria. He also found that the 

 staining reaction of the incubated mitochondria varied 

 under these conditions. Jessen ('25), produced degen- 

 eration of mitochondria in kidney cells by the injection of 

 bacteria, diphtheria toxin and distilled water. 



In the experunents described in the preceding chapter, 

 it was noted that the cultured mitochondria did not always 

 have the same morphology as those in the normal hver 

 tissue. This pecuharity was noticed in the first surface 

 growths that were obtained. A large series of subculture 

 experiments were made from the initial growths in order to 

 study more minutely the pleomorphic possibihties of the 

 cultured mitochondria. 



The first subculture experiments were made with a coccus 

 which developed in a rabbit liver medium eight days after 

 it had been planted with hver from a new-born rabbit. 

 When the organisms were subcultured into beef heart media 

 of various hydrogen-ion concentrations from pH 7.1 to 

 pH 7.5, the growths in these media varied in size according 

 to the pH value of the medium. It was possible to trans- 

 plant any of these subcultured organisms into a medium 

 with a particular pH value and obtain organisms of a uni- 

 form size. After these cultures had been kept a little more 

 than a year in cold storage, they were found to have lost 

 their specific response to the hydrogen-ion concentration 

 of the medium. The size would vary in media of different 

 pH values, but the variations were erratic in character. 



A large number of subcultures were made from the initial 

 growths that developed in the urea and tryptophane media. 

 The highly specific response obtained in the earlier subcul- 



