CHEMISTK.Y AND VIRAL GROWTH 



(2), and can be stripped off in a Waring blendor without affect- 

 ing the subsequent course of the infection (27). A spurious in- 

 jection, simulating osmotic shock, can be observed when virus 

 particles react with specific substances of bacterial origin (32), 

 or even with an ion-exchange resin (52). The material released 

 in this way consists of fibers 20 A or more in diameter and several 

 microns per phage particle in aggregate length (32,67). The 

 visible fibers are destroyed by deoxyribonuclease (32). Their 

 number has not been counted. 



Several of the facts mentioned seem to show that injection 

 occurs independently of bacterial metabolism. Benzer (4) 

 finds, however, that an external food supply is required. The 

 ability of the virus to inject resists multiple lethal doses of ultra- 

 violet light, but is nearly as sensitive as the infective property to 

 formaldehyde and ionizing radiations (27,29). At present a 

 satisfactory m.echanism of injection cannot even be imagined. 



Whatever the details of injection, it seems permissible to con- 

 clude that a resting particle of T2 consists of a protein syringe 

 that functions chiefly to get the viral DNA into the cell, and that 

 only the injected materials, and possibly the nonstrippable stub 

 of the tail (amounting to 20 per cent of the total protein of the 

 virus particle), participate directly in viral growth. 



VEGETATIVE PHAGE 



The events that follow injection are strictly dependent on a 

 source of nutrients external to the cell, except that starved, 

 infected cells tend to lose their potentiality to yield virus. Given 

 adequate food and a favorable temperature (usually 30° to 

 37° C), the normal course of events leads to cellular lysis with 

 the liberation of 20 to 2000 new viral particles per bacterium, 

 the yield depending chiefly on nutrient conditions and the length 

 of time (20 minutes to about 2 hours) during which cellular lysis 

 can be delayed. 



Beginning with the injection, marked changes occur in the 

 biosynthetic pattern of the cell. These changes will be described 

 presently, but do not yet help to define vegetative phage, which 



