476 THE BACTERIOPHAGE AND ITS BEHAVIOR 



In order to gain information on these two points we have procured blood by 

 venepuncture from a group of 11 apparently healthy individuals. In none of 

 these did we ever succeed in demonstrating a lytic principle. 



We have also examined the blood of various domestic animals, — sheep, chick- 

 ens, and horses, — and in healthy animals of all of these species a lytic principle 

 has never been found. 



And finally, in order to afford an additional check on the results reported above, 

 we made examinations of the blood of persons suffering from diseases other than 

 typhoid fever (2 cases of tuberculous meningitis, 2 cases of pulmonary tubercu- 

 losis, and a number of cases of various infectious diseases). In no case could a 

 lytic principle active for B. typhosus be disclosed. 



With reference to the other point at issue, it should be stated that the filtrates 

 which gave the d'Herelle phenomenon were subjected to the following tests: 



First, serial transmissibility of the action: 



Second, susceptibility to heat inactivation, with the possible reactivation. 



The lytic principles which we recovered from the blood stream of our patients 

 showed differing susceptibilities to heating, the sensitivity being related to the 

 virulence of the principle. Most of them were inactivated at 70°C., a few at 

 temperatures between 75 and 80°C.* Reactivation was always possible. 



Third, the formation of clear plaques on agar slants. 



The fact that the principles found by us in these cases conformed in all of these 

 respects to the reactions induced by the bacteriophage clearly proves that they 

 were, indeed, races of the bacteriophage with which we were working and not some 

 bacteriolytic property of the serum as we have been accustomed to conceive the 

 latter. 



I may add that I have never found in the blood the bacteria-dissolving princi- 

 ple, not bacteriophagous in nature, which has been reported to be present in 

 stools. t 



Such are the conclusions of Hauduroy, and he ends his discussion 

 in these words: "We can not summarize our observations better than 

 to borrow from d'Herelle one of his conclusions, namely, that in every 

 case (of typhoid fever) the condition of the patient registers faithfully 

 the fluctuations in the struggle taking place within the body between the 

 bacteriophage and the invading bacterium." 



I may contribute something to one point brought out in the studies 

 of this author. I have had an opportunity to examine four blood 



* Heating in an open tube for 5 minutes. 



I I have noted in the stools of cholera convalescents, and even in those of 

 persons who have received injections of heat-killed cholera vibrios'^^ a principle, 

 oi ferment nature, capable of dissolving the cholera vibrio. Hauduroy has found 

 this same fermenting principle in the intestinal tract in patients convalescent 

 from typhoid fever. Most certainly this principle is derived from the body of the 

 patient, and has nothing in common with the bacteriophage (it is effective in pro- 

 portion to its concentration; its action is not transmitted in series). Surely it 

 plays some role in immunity, and offers a problem worthy of study. 



