436 BACTERIOPHAGES 



type specimen as an individual has been shown to be inade- 

 quate and has been replaced by the total gene reservoir of an in- 

 terbreeding population, which places a limit on the variability 

 of the individuals within that population. When we turn to 

 phage taxonomy we find species named and described in terms 

 that make identification impossible in the absence of any known 

 type specimens for comparison (Holmes, Bergey's Manual) . In 

 such a taxonomy no attempt is made to describe the liinits of 

 variability of different strains within a species. 



One of the principal taxonomic characteristics used in all 

 schemes of phage classification is serological specificity as demon- 

 strated by the neutralization test. Yet this characteristic is 

 worthless unless one has either a type specimen for direct com- 

 parison, or at least a sample of serum containing the appropriate 

 antibodies. As noted above in discussing the serological cri- 

 terion, variability within a species may be suflficiently great so 

 that one type strain or antiserum is not adequate to describe the 

 species. 



The significance of preserving type strains will be evident when 

 it is noted that only a few of the type strains for Burnet's eleven 

 serological groups of coli-dysentery phages are still available, in 

 spite of the great amount of work done with these phages and in 

 spite of the fact that they are included in Holmes' taxonomic 

 scheme. These serological groups may well remain forever 

 unidentifiable unless the original strains are recovered. 



Until recently there was no type culture collection of bac- 

 teriophages in existence and only a few private collections of any 

 size. In 1954 the American Type Culture Collection, Washing- 

 ton, D.C., started a section for phage strains and their host cells 

 and a fairly representative collection is available from this 

 source. Other major collections are those of Asheshov, Lister 

 Institute, London; Boulgakov, Institut Pasteur, Paris; and the 

 collection of typing phages of the Public Health Laboratories in 

 Colindale, London. 



It is proposed that whenever a new phage strain is described in 

 the literature attempts be made to identify it by comparison with 



