BACTERIOPHAGOUS ULTRAMICROBE 121 



It has likewise been shown that a bacteriophage active for the 

 staphylococcus and maintained through more than one hundred 

 transfers with this staphylococcus still possessed virulence for 

 the dysentery bacillus. And it is also possible to effect, in vitro, 

 the adaptation for this Shiga bacillus of a strain of bacteriophage 

 active only for Staphylococcus aureus. The staphylococcus and 

 B. dysenteriae are bacterial species but remotely related and the 

 crossed reaction constitutes an irrefutable argument in favor of 

 the unicity of the bacteriophage. 



Third. An antibacteriophagous serum, the properties of which 

 will shortly be considered, contains an amboceptor specific for 

 the bacteriophage, as is demonstrated in the complement fixa- 

 tion reaction of Bordet-Gengou, and this amboceptor is the 

 same for all species of bacteriophage — the anti-dysentery bac- 

 teriophage, the anti-plague bacteriophage from man, the anti- 

 plague bacteriophage from the rat, and the anti-barbone bac- 

 teriophage from the buffalo, all fix complement in the presence 

 of serum from a rabbit treated by repeated injections of cultures 

 of the anti-dysentery bacteriophage. 4 For this particular ex- 

 periment strains of bacteriophage were selected which failed to 

 show a crossed reaction in vitro with regard to the different bac- 

 teria attacked. The complement fixation reaction is specific 

 with respect to species differentiation. 



The proofs of the unicity of the bacteriophage are therefore 

 multiple. There is but a single bacteriophage, common to both 

 man and animals, capable by adaptation of acquiring a virulence 

 toward all bacterial species. 



As we have seen in the earlier chapters the bacteriophagous 

 ultramicrobe can not be cultivated in any artificial medium. It 

 is an obligatory parasite, capable of reproduction only within 

 living cells. Moreover, this is the case with all known ultrami- 

 crobes. The single one making the exception to this rule, the 

 Asterococcus of pleuropneumonia is hardly longer to be consid- 

 ered as an ultramicrobe, since it has been shown to be perfectly 



4 Since the publication of the French edition of this text Bruynoghe 

 and Maisin have confirmed this fact. They have also shown that fixation 

 of complement is also to be obtained with an anti-staphylococcus bacterio- 

 phage under the conditions already mentioned. 



