510 GENETICS OF SOMATIC CELLS 



This suggests, of course, that we must be very cautious in applying in vitro results 

 to whole animals. We must compare results for situations in vitro and in vivo and 

 establish their relationships before we can substitute the quicker and easier measure- 

 ment in vitro for those made in vivo on whole animals. 



ADDENDUM 



Preservation of a large number of normal and malignant strains and lines of 

 Chinese hamster and human origin beyond four months storage by means of dry-ice 

 refrigeration has been hampered because of fluctuations in temperature (-50 to-69°C). 

 Recently, the adaptation to liquid nitrogen (-179°C) as a refrigerant for prolonged 

 storage has greatly advanced the mechanics of handling and assuring viability of 

 many strains currently being characterized by the Cell Culture Collection Committee 

 of the U.S. Public Health Service, National Institutes of Health, Bethesda 14, Maryland. 

 Information regarding the use of liquid nitrogen may be obtained from the Linde 

 Corporation, 30 East 42nd Street, New York, New York. 



The recent (June, 1961) Syverton Memorial Symposium on "Analytic Cell 

 Culture," edited by Robert E. Stevenson, is now available as The National Cancer 

 Institute Monograph No. 7, April, 1961, and may be obtained from the Superin- 

 tendent of Documents, U.S. Government Printing Office, Washington 25, D. C. Price: 

 §2.25. Among other topics, recent observations in the preservation and characteri- 

 zation of cell cultures are discussed by H. T. Meryman, C. S. Stulberg, L. L. Coriell, 

 and E. H. Y. Chu. 



