654 



GROWTH OF PHAGE AND LYSIS 



30 



20- 



0* 



20 30 40 50 60 70 



80 



Fig. 5. One step phage growth on 24 hour aerated bacteria. Direct plot. 



At time zero 2 X 10^ phage/cc. were added to 1 cc. of a 24 hour stock culture of 

 bacteria, containing 2 X 10^ bacteria/cc. After 5 minutes free phage were determined 

 and suitable high dilutions in broth were further incubated at 37° with aeration. At 

 intervals samples from these mixtures were plated for plaque count. 



It is seen that the plaque count stays constant for 30 minutes, then increases linearly 

 with time till about 50 minutes when it reaches twenty times the original value. After 

 50 minutes it stays nearly constant. Phage liberation takes place uniformly during 

 20 minutes. 



g r"-A.-o s e 6 o 



ujd- ° 



3 

 O 

 < 



2 

 o 

 081- 



Lysfs 



,-->^' 



.TIME , IN (VHNUTE3 



5 10 15 20 25 30 35 40 



Fig. 6. Addition of a great excess of phage to a growing culture of bacteria, at 37*^ 



68 



