ADAPTIVE CHANGES OF BACTERIAL CULTURES. 3 



the destructive action of these cells and consequently develop and 

 multiply with greater security; or, indeed, they may secrete more 

 abundant or more dangerous toxic products than before. 



These two causes may operate simultaneously. It is necessary 

 then to compare, first, the chemiotactic influence of the original or 

 normal organism with that of the "modified" organism, and second, 

 the toxic properties of the substances formed by these two strains 

 of vibrios. 



Experiment 1. The four different organisms were grown in a 

 special fluid that offers a good culture medium which has already 

 been used by J. Massart and Ch. Bordet; this medium has in itself 

 not the slightest chemiotactic effect on leucocytes. 



After three days of growth at 32° C, capillary tubes are filled 

 with these virulent cultures and placed in lots of a dozen in the 

 peritoneal cavity of a normal guinea-pig. They are removed 8 

 hours later, when it is found that the columns of leucocytes that 

 have entered the tubes vary in length. In the tube containing the 

 normal vibrio, cultivated for several months on agar, the length of 

 this column is the same as with the normal vibrio recently isolated 

 from the tissues of an unvaccinated guinea-pig. With the vibrio 

 modified by a single passage through a vaccinated guinea-pig the 

 column is about half that of the preceding. With the organism 

 modified by two passages it is slightly less than half. 



The same experiment was performed with cultures sterilized at 

 115° C. No difference in the influx of leucocytes was noted. 



It is evident, then, that the attracting power for leucocytes is 

 notably less in organisms grown in immunized guinea-pigs than in 

 the two normal organisms; one that was passed through a normal 

 guinea-pig and the other grown for a long time on artificial media. 



It is rather interesting to note that there is no appreciable dif- 

 ference between these last two strains of vibrio. The chemiotactic 

 properties evidently have not been altered by growing on agar. 



What is more, it may be mentioned that we have found that the 

 vibrio Metchnikovi in old cultures exposed to the air is little, if at all 

 attenuated; a culture bearing the date Dec. 16, 1S91, and inoculated 

 March 29, 1892, in a dose of 0.5 c.c, killed guinea-pigs in 20 hours. 

 As is well known, many pathogenic organisms attenuate more 

 rapidly. 



