CHEMICAL COMPOSITION 95 



from measurements of this type. The ratio of nitrogen to phos- 

 phorus indicates that the material consists of phage particles 

 but the plaque count is improbably low. The phosphorus (or 

 nucleic acid) content per particle is important for several reasons 

 (Stent, 1958) and reliable ways to determine it need to be de- 

 veloped. 



8. Summary 



The few phages that have been analyzed contain deoxyribo- 

 nucleic acid and protein in approximately equal amounts and 

 very little else. This distinguishes them from most living things 

 including most of the other viruses, excepting perhaps certain 

 animal sperm and some insect viruses. 



A few phages, notably T2, contain a chemically unique nucleic 

 acid. Phage proteins have been relatively little studied. Most 

 of the protein of T2 is membrane material. It is not unusual 

 with respect to amino acid composition. 



