INTRODUCTION 19 



dysentery (B. dysenteriae Shiga) was under treatment in the 

 Pasteur Hospital. Each day an examination of the feces from 

 this patient was made by the inoculation of bouillon with some 

 of the fecal material. After incubation at 37°C. for over night 

 the growth was filtered through a Chamberland filter. To a 

 second tube of broth, previously inoculated with a culture of the 

 Shiga bacillus, twelve drops of the filtrate were added and the 

 culture so treated was returned to the incubator. Throughout 

 the period of the infection, all of the tubes, prepared each day 

 in the same manner, yielded normal growths of the dysentery 

 bacillus. One day, examination of the tube prepared the day 

 before showed no growth, and investigation showed that the 

 patient presented symptoms indicative of marked improvement. 

 Definite convalescence rapidly followed. The bouillon which 

 had been inoculated with both culture and filtrate was to all 

 appearances sterile, and to this was again added a suspension of 

 Shiga bacilli taken from a young agar culture. The inoculation 

 was sufficiently heavy to present a definite turbidity, but after 

 incubation for twelve hours it was again clear. The excreta 

 from which the filtrates were prepared contained, then, a prin- 

 ciple which dissolved the dysentery organisms. 



When a drop of the lysed culture was added to a young bouillon 

 culture of the Shiga bacilli this culture in turn became dissolved. 

 In the same way, several successive passages were accomplished, 

 introducing each time a drop of the culture previously lysed into 

 a fresh culture of the Shiga strain. Instead of losing in potency 

 through such passages it increased in lytic capacity; the dissolv- 

 ing action being accomplished more and more rapidly. From 

 this it was evident that the lytic principle derived from the ex- 

 creta was capable of cultivation in series. 



When a very minute amount (0.00,001 cc.) of one of these 

 lysed cultures was added to a young broth culture of the Shiga 

 bacillus and then this mixture was tested immediately and again 

 after incubation periods of one, two, and three hours, a drop of 

 the material being inoculated on to agar slants, the latter showed 

 after incubation very interesting characteristics. In the first 

 tube thus inoculated the agar was covered by a normal film of 

 dysentery bacilli, but with two circular areas about 2 mm. in 



