84 Essays in Biochemistry 



and lysis of the cell. If the body were incorporated into another cell 

 and again interrupted cytidine synthesis as it continued its own multi- 

 plication, it would evidently be a virus. Perhaps this type of un- 

 balanced growth accounts for the origin of some of these parasites, 

 whose properties more nearly resemble parts of cells than intact cells. 

 Perhaps this hypothesis can also be tested in the near future. 



References 



1. N. W. Pirie, New Biology, 16, 41 (1954). 



2. G. R. Wyatt and S. S. Cohen, Biochem. J., 55, 774 (1953). 



3. S. S. Cohen, Cold Spring Harbor Symposia Quant. Biol, IS. 221 (1953). 



4. H. D. Baraer and S. S. Cohen, ./. Bacterial, 68, 80 (1954). 



5. S. S. Cohen and H. D. Barner, Proc. Nat. Acad. Sci. U. S., 40, 885 (1954). 



6. D. Kanazir and M. Errera, Biochim. et Biophys. Acta, 14, 62 (1954). 



