464 THE BACTERIOPHAGE AND ITS BEHAVIOR 



A number of authors, basing their opinions on their own studies, 

 have taken exception to these conclusions. They have filtered a speci- 

 men of stool taken from a person at any time during the convalescent 

 period, they have combined this filtrate with any typhoid bacillus that 

 happened to be available, and they have found that the filtrate was 

 inert. From such a study they concluded that their observations did 

 not support my conclusions. Most assuredly their results did not con- 

 form to mine, nor did their procedure resemble the method which I 

 employed. I have, upon several occasions, insisted upon the mode of 

 procedure to be followed by those who wish to correctly disclose the 

 facts, and if I have insisted on this, it is simply because I am convinced 

 that to follow any less exacting method is to invite precisely those errors 

 which have been committed, together with the faulty deductions con- 

 sequent to them. It is only necessary to consult the curves presented 

 above to see that, in the majority of cases, the bacteriophage does not 

 retain its virulence for the pathogenic bacterium. Immediately after 

 the in vivo bacteriophagy is completed the virulence disappears. Fur- 

 thermore, we know very well that B. typhosus is a heterogeneous species 

 as regards the bacteriophage, and to take any strain of this bacillus at 

 all in order to determine whether the race of bacteriophage present in a 

 patient is virulent for B. typhosus is simply to confess that the nature 

 of the phenomenon of bacteriophagy is not too thoroughly appreciated. 



There is but a single method which will allow one to determine the 

 behavior of the bacteriophage in the course of disease in general and 

 in typhoid fever in particular, and that method consists in the daily 

 collection of specimens of the stools of the patient, from the beginning of 

 the disease up to the end of convalescence, and in combining filtrates of 

 the specimens so obtained with cultures of the pathogenic bacterium isolated 

 from the patient himself at the beginning of the disease. 



To work in any other way, and then declare that the results do not 

 agree with mine, is to beg the question. 



One author only has applied this rational method to his studies, and 

 that is Hauduroy.2^* 



As this question of bacteriophagy in vivo is of fundamental importance 

 in its bearing on the new conception of immunity, I am inserting here, 

 in extenso, some of the statements made in Hauduroy's paper. He 

 states : 



It is not possible to reproduce here all of the curves and all of the observations 

 which I have made. I shall content myself with recording a few selected cases 

 taken from among those which seem to me to be the most typical. 



