STAGES IN PHAGE MULTIPLICATION 185 



to explain the failure of doughnuts to accumulate in response to 

 the drug. However, the effect of proflavine may be more com- 

 plicated (Chapter XV). 



Kellenberger and Sechaud were able to count tail pins as well 

 as doughnuts (Chapter IV). Tail pins did not appear until 

 phage particles had already become very numerous, and finally 



Figure 7. Products of lysis by T2 in the presence of proflavine. Intact 

 phage particles, empty heads, tail pins and, in the upper part of the micro- 

 graph, fibrils that may be DNA. X22,125. Reproduced from E. Kellen- 

 berger and J. Sechaud, 1957, Virology, 3, 256, with permission. 



numbered about 30 per bacterium. Their formation was not 

 affected by proflavine. The delayed appearance of tail pins 

 might suggest that they are products of defective synthesis or 

 breakdown of phage particles, rather than precursors, in which 

 case some of the doughnuts might originate in a similar way. 



Kellenberger and Sechaud found that tail pins of T2 adsorb in- 

 completely and mostly reversibly to bacteria. They do not react 

 with the neutralizing antibody of antiphage serum. 



