90 



II. FUNDAMENTAL STRUCTURE OF PROTOPLASM 



occurrence of lysis is shown in Fig. 15 (104). As already mentioned, 

 host cells usually multiply more rapidly on the infection with a 

 virus ; also in this respect phage presents no exception. However, it 

 must be emphasized that a certain phage, which can promote in broth 

 the bacterial growth in such a manner, can render the bacteria non- 

 viable on agar plate. 



K 



8 2t 



Time in hours 



Fig. 15. Clearing of the bacterial suspension by phages of both large 

 and small plaques. Strain: B. dysenteriae (KA 1). 



The broth-suspension of the bacteria (number of the viable bacteria : 1 x 

 lO^cc.), to which the phage filtrate has been added, is placed in a water 

 bath at 37°C. and the clearing degrees are observed nephelometrically with 

 Pulf rich-photometer. 



I, II and III are the suspensions to which the large plaque phage (average 

 plaque diameter ; 2,6 mm.) has been added so that the concentrations of the 

 active particles become IxlC, 1x10^ and IxlO^/cc. 1, 2 and 3 are the sus- 

 pensions to which the small plaque phage (average plaque diameter ; 0,5 mm.) 

 has been added, particle concentrations being equal to I, II, and III respec- 

 tively. C is the control suspension to which no phage has been added. 



