FATE OF INFECTING PHAGE PARTICLES 217 



the infected bacteria by vigorous shaking without affecting 

 phage development. These facts in themselves imply that 

 little or no transfer of phage protein from parent to progeny 

 should be expected. However, prior to this discovery there were 

 several papers which indicated that phage protein was indeed 

 transferred to progeny. It is worth while to discuss these experi- 

 ments briefly as an indication of the type of technical error which 

 can result in false conclusions. In a brief report Hershey, Roe- 

 sel, Chase, and Forman (1951) stated that about 35 per cent of 

 the sulfur of infecting T2 phage was found in the phage progeny, 

 and that when this phage progeny was used in a second cycle of 

 infection, 40 per cent of its sulfur was found in the second cycle 

 progeny. Since only the phage protein is labeled in sulfur, 

 these experiments were interpreted as transfer of parental pro- 

 tein to progeny. The transfer of about 18 per cent of parental 

 T6 phage N'^ to progeny was reported by Kozloff (1952b). 

 The apparent transfer of protein N was not equal to the transfer 

 of nucleic acid N, and the ratio of the two was not constant from 

 one experiment to another, varying from 0.4 to 0.9. Kozloff 

 (1952c) concluded that nucleoprotein was not transferred from 

 parent to progeny as a unit, but that there was extensive rear- 

 rangement of the contributed parental material which suggested 

 the use of breakdown products of the infecting virus for synthesis 

 of protein and DNA of the progeny virus. 



The earlier reports of the transfer of parental protein to 

 progeny were demonstrated by Hershey and Chase (1952) to be 

 the result of unsuspected contamination of progeny phage with 

 protein remnants of the infecting phage. If, after infection with 

 sulfur-labeled phage, the bacteria were agitated in the Waring 

 Blendor, centrifuged to eliminate the dislodged membranes, and 

 then permitted to lyse in a fresh medium, the isolated phage 

 progeny was found to contain only one per cent of parental sul- 

 fur. Therefore there is no obligatory transfer of sulfur-contain- 

 ing proteins from parent to offspring. Under the usual condi- 

 tions of multiple infection there is a considerable spontaneous 

 elution of phage membranes which cannot be distinguished from 



