350 



OHNO. 



From the experiments given in the tables above it may be seen that 

 different strains of the cholera vibrio react differently toward acid and 

 alkaline solutions, and that the medium in which the morphology 

 appears most typical is different foi- the different strains. Therefore, 

 it follows that peptone solutions of different reaction should be used 

 in isolating the cholera organism in cultures, and, as I have stated, 

 I believe that at least three different peptone solutions are necessary 

 to obtain the best results. 



The cholera vibrio shows a great adaptability to culture media of 

 different reaction. For example, if we inoculate a strain of the cholera 

 vibrio into 3.5 per cent alkaline peptone solution in which the organism 

 at first develops but slightly and appears in a spherical form, in the 

 course of a number of passages through peptone of the same reaction 

 the rapidity of growth in this media increases and it finally regains 

 its original size and thickness and its typical form. (See Table 6.) 



Table 6. — Adaption of cholera vibrio to alkaline media. 



Strain. 



First generation. 



Third generation. 



Fifth generation. 



liighth generation. 

 Well developed. 



"Marga- 



Slight develop- 



Slight develop- 



Development mod- 



rita 1". 



ment of spheri- 



ni e n t, some 



erate, most 



typical forms. 





cal forms. 



curv ed, some 

 oval forms. 



forms curved, 

 some oval. 





"Juan" 



Very slight devel- 



Slight develop- 



Development mod- 



Well developed, 





opment of sphe- 



ment, some 



crate most 



typical forms. 





rical forms. 



curved, some 

 oval forms. 



forms still oval. 





"Engra- 



Slight develop- 



Development mod- 



Development 



Well developed. 



cial". 



ment of spheri- 



erate, most 



marked, most 



typical forms. 





cal, oval and 



forms curved and 



forms curved, 







thick curved 



of still s m al 1 e r 



thick, and large. 







forms. 



size. 







"Leon I"- 



Slight develop- 



Slight develop- 



Development mod- 



Well developed. 





ment of coccus 



ment, all oval 



erate, some oval. 



all formscurvod. 





forms. 



forms. 



some curved 



thick, and short. 









forms. 





This adaptability can also be demonstrated in a single inoculation of 

 the culture media, when the quantity of peptone present is sufficient to 

 furnish nutritive material to the strain for a long period of time. The 

 adaption takes place slowly, so that if we inoculate a strain which is 

 highly adapted to an alkaline medium on acid culture media, the 

 morphology of the vibrio changes at first to that of a rod or to an oval 

 or spherical form. When this strain is adapted on the acid medium, on 

 re-inoculating it on the original alkaline culture niedia it appears in oval 

 or spherical form even if its morphology was typical formerly on this. 



