196 BACTERIOPHAGES 



sum. When applied to phage-infected bacterial cultures during 

 lysis it enabled him to see a halo of adsorbed phage particles sur- 

 rounding the yet unlysed bacteria. Although this procedure 

 may have permitted visualization of extracellular phage particles, 

 it did not contribute to knowledge of the infectious process. 

 Hofer (1947) also used a flagellum stain and the Ziehl-Nielsen 

 stain in an attempt to color extracellular phage particles but 

 again without yielding much information about phage multipli- 

 cation. His claim to have seen phage particles under these con- 

 ditions is not convincing. 



A remarkable paper by MacNeal, Frisbee, and Krumwiede 

 (1937) described the application of the Casteneda rickettsial 

 stain to the study of the lysis of the cholera vibrio by phage and 

 by antiserum plus complement. The phage-infected bacteria 

 were pleomorphic, enlarged and distorted, and filled with as 

 many as 50 tiny blue-staining granules per cell. Such granules 

 were never seen in normal bacteria, nor in bacteria undergoing 

 lysis by complement and antibody. It seems very probable that 

 the granules were intracellular phage particles. This work does 

 not seem to have been followed up nor to have attracted much 

 notice. 



The first applications of chromatin-staining procedures to the 

 study of phage-infected bacteria seem to have been made by 

 Luria and Palmer (1946) and by Beumer and Quersin (1947). 

 Luria and Palmer used Feulgen and Giemsa stains following the 

 general procedures of Robinow (1944). Infection with phage 

 T2 resulted in the disorganization of the nuclear bodies and mi- 

 gration of the chromatin to the periphery of the cell. The cells 

 then gradually filled up with granular chromatin. Phage Tl 

 caused relatively little change in the appearance of most cells. 

 Infection with phage T7 caused great swelling of some nuclear 

 bodies and shrinking of others. The different phages caused 

 characteristically distinct cytological changes in appearance of 

 the host cell nuclear apparatus. 



Beumer and Quersin (1947) and Quersin (1948) used Robi- 

 now's staining techniques to study the cytological changes pro- 



