i6o 



Scientific Proceedings (113). 



colonies whether they be derived from a typhoid, Shiga or Mt. 

 Desert cultures act in the same way. The lytic principle in the 

 experiments thus far has showed no variations due to the fact that 

 it was carried along by typhoid or dysentery cultures. I have, 

 therefore, worked almost exclusively with the derivatives of 

 dissolved typhoid cultures. The stock typhoid and dysentery 

 cultures used in these experiments have been repeatedly streaked 

 out without obtaining the irregular type of colony which is the 

 bearer of the lytic principle. This type of lytic colony has, as 

 far as I know, not been described by d'Herelle, but was first 

 reported by Bordet in connection with the lytic principle that 

 he was able to produce in the peritoneum of guinea pigs by repeated 

 injections of B. Coli. 



If one of these irregular colonies, whether typhoid or dysentery, 

 is streaked out, a certain number of typical round colonies develop 

 which, when fished into broth, will make the broth turbid. Typical 

 colonies have never, in my experience, given anything but typical 

 colonies on restreaking. Usually on restreaking an irregular 

 "lytic" colony the majority of colonies obtained will be of the 

 lytic variety, although I have found it very difficult to gauge the 

 proportion of typical and lytic colonies that will be obtained 

 from any given lytic colony. If a series of lytic colonies are 

 obtained in this way in a row, it will be found, on examining 

 under the microscope, that there are often minute transparent 

 masses between the lytic colonies, and have been called "appear- 

 ances" by previous observers. On examining the irregular lytic 

 colonies under the microscope it will be found that the lytic 

 colonies owe their irregular shape to the fact that their edges 

 have faded out into these transparent "appearances." It is 

 impossible to predict the amount of "appearances" that will be 

 obtained by restreaking lytic colonies, and varying degrees of 

 transparency occur in the "appearances." Fishings of the most 

 transparent type of "appearances" have failed in most instances 

 to produce any growth on a variety of media. When growth did 

 occur it proved to be colonies of the lytic type. Comparative 

 fishings of lytic colonies and "appearances" into young turbid 

 broth cultures of typhoid were made to see if the lytic principle 

 was carried by the "appearances"; the former usually became 



