Fig. 6. (a) To attached tail-lirst to a host cell. The, heads of several of the particles 

 appear empty, indicatmi; that the DNA has been injected (Magnification • 27,000) 

 (Courtesy of T. Anderson); (b) Mixture of To and a cellular component containing the 

 attachment site for To. For comparison, see Fig. 1(a). The cellular component is the 

 smaller spherical structure that has become attached at the tip of the phage tail. Note 

 that in several particles that have reacted with the cellular component the heads appear 

 empty (Magnification X 41,000). (From Woidol and Kellenberger, 1955.) 



