DISSOCIATION AND TRANSFORMATION 173 



all differences, were really linked together. He claimed to have ob- 

 tained mutations by gradual adaptations of the organisms to the 

 host. The attempts met with many failures which were explained by 

 saying that if the organism was too weak it died in the host, and if 

 too virulent it killed the host before any accommodation had taken 

 place. Wolff asserted, however, that in three cases he had trans- 

 formed Streptococcus viridans from endocarditis lenta into Pneu- 

 mococcus. The organism became bile-soluble, optochin-sensitive, 

 developed a capsule, fermented inulin, and was lethal for mice. 

 Evidence of bacterial mutations of any kind coming solely from in 

 vivo experiments is to be weighed with caution. 



Neufeld 979 in a discussion already cited on microbic variability, 

 recalled an observation he had made ten years previously on the 

 original "Pneumococcus I" of Neufeld and Haendel, which had 

 been preserved by drying and storage in a dessicator. One mouse 

 inoculated with the culture produced a strain growing in chains, 

 insoluble in bile, but virulent for mice, and with all typical strepto- 

 coccal properties. At first Neufeld thought he had made a mistake 

 in the material he injected, but a similar experience of Schiemann's 

 convinced him that a mutation had actually taken place. Coming 

 from anyone less eminent than Neufeld, this single, isolated obser- 

 vation would be disregarded. 



In the following year, Morgenroth, Schnitzer, and Berger 929 an- 

 nounced that by special methods they had been able with regular- 

 ity to transform pneumococci into streptococci.* Their medium 

 contained dead yeast cells or animal charcoal which had adsorbed 

 optochin. The altered strains became insoluble in sodium tauro- 

 cholate, were avirulent for mice, and were resistant to optochin. 

 Modification A represented the first stage in the transmutation. 

 The organisms retained the majority of their pneumococcal char- 

 acters, but were more resistant to optochin and more sensitive to 



* Stankaisi2 called attention to the fact that these authors had omitted men- 

 tion of similar work published by Elschnig and Ulbrich, and by Kraupa from 

 the German Eye Clinic at Prague. 



