CHAPTER XII 



CONCLUSIONS 



1. Variation occurs in every character of bacteria. 



2. These variations may be either " spontaneous " or " im- 

 pressed " by conditions of environment. 



3. The recognition of " species " amongst bacteria must, 

 therefore, depend upon a consideration of their biological 

 characters as a whole and upon the stability these characters 

 display. 



4. Transmutation differs from variation in degree alone ; 

 it is a question of the extent of the modification and the de- 

 gree of permanence it exhibits. 



5. Transmutation differs from evolution in degree alone ; 

 it is a question of the rapidity of the change. 



6. The occurrence of transmutation between closely allied 

 organisms in the human body is not capable of proof but is 

 suggested by circumstantial evidence. 



7. Supposed instances of transmutation, brought about by 

 experimental inoculation of animals, are shown to rest on in- 

 conclusive evidence. 



8. The Enzyme theory of disease suggests a means by 

 which bacteria may exchange many of their characters and 

 functions without themselves undergoing transmutation. 



