546 



THE BACTERIOPHAGE 



in the case of cells which disappear after having undergone only moderate swelling. 

 Extremely swollen cells leave practically no trace after their sudden disappearance. 

 The rapid melting away of the bulk of the cytoplasm (which under ordinary cir- 

 cumstances is supposed to be semi-gelatinous in consistency) suggests that it probably 

 was liquefied within the cell prior to the disappearance of themembrane. A similar con- 

 clusion is suggested also by the appearance of bacteria in the stained preparations. 

 When swollen bacteria are stained by the method of Gutstein/ the cytoplasm may be 

 differentiated from the ectoplasm. The latter always appears continuous, and even 

 in extremely distended cells it shows no evidence of "holes" described by D'Herelle^ 

 as resulting from the puncturing of the membrane by the entering parasites. The 



Vic. (). — StctitJii of a cinematographic record, representing three successive exposures taken at 

 2.5 seconds' intervals and showing disappearance of a moderately swollen cell. Magnification X 1,500. 



cytoplasm, on the contrary, shows marked changes during swelling. It takes the 

 stain less intensely and less evenly as the swelling progresses, so that in many in- 

 stances it appears segmented or beaded (Fig. 7)^ In cells photographed at this stage 

 unstained, by means of ultra-violet light illumination,4 the cytoplasm appears to be 

 of uneven density, quite unlike that of normal bacteria. Some of the stained prepara- 

 tions of highly swollen bacteria suggest that the material which normally binds the 

 chromatin has become digested, and the chromatin distributed throughout the cy- 

 toplasm in minute dust-like particles (Fig. 8). 



If the conclusion drawn from these observations is correct, the cytoplasm must 

 have undergone digestion during the progress of swelling, so that when it was set 

 free, following the disappearance of the cell wall, it went immediately into solution. 

 If such were the case, however, chemical examination of the solution should show the 

 presence of products of digestion. As stated previously, repeated analyses of lysed 

 cultures have failed to indicate the presence of such products.^ The failure of these 

 attemipts to detect hydrolysis might have been due, however, to the fact that the ma- 



' Gutstein, M.: Ccnlralbl. J. Baklcriol., Orig., 100, i. 1926. 



' d'Herelle, F.: The Bacteriophage and lis Behavior, p. 115. 1926. 



3 Somewhat similar changes were brought out also by the toluidin staining by von Preisz {loc. cit.). 



'^ These photographs were secured through the kindness of Dr. F. Gates. 



5 Weiss, E., and Arnold, L.: loc. cit.; lonesco-lMihaesti, C.: loc. cit ; Zdansky, E.: loc. cit. 



