t2 and other bacterial viruses 



461 



empty^; (3) that in infected host cells prematurely lysed or in infected host cells 

 treated with proflavin one finds so-called "donuts" (resembling viral head- 

 pieces), as well as particles resembling viral tails. These are noninfectious, 

 protein in nature, and possess the serological characteristics of the intact 

 infectious particle. 



III. The Protein Components of Coliphage Particles 

 A. Amino Acid Content of Coliphage Proteins 



Table I represents a summary of the available analytical data for the 

 amino acid composition of the proteins from coliphages T2, T3, and T4 in 

 comparison with representative figures for the amino acid composition of the 

 proteins of Escherichia coli B. 



Table I 

 Amino Acid Composition of Coliphage and E. coli Protein <* 



•* Calculated from references given. Expressed as per cent of total amino acids 

 analyzed. 



^ Fraser (1957). c Poison and Wyckoff (1948). 



<* Roberts et al. (1955). « Poison (1948). 



^ It is the usual experience to find that ghost preparations before treatment with 

 DNAase contain variable amounts of DNA. Whether this represents a fragment of DNA 

 still incorporated in its original state in the particle or the adsorption of a portion of th e 

 liberated DNA to the external surface of the ghost particle is not known. 



