280 THE BACTERIOPHAGE AND ITS BEHAVIOR 



in the distillate. This result is not peculiar to one race alone, for 

 absolutely identical results were secured with races virulent for Shiga, 

 B. pestis, B. coli, B. typhosus, and for the staphylococcus. 



Gildemeister and Herzberg,-^^ Borchardt,^^ Spat,^^^ Bronfenbrenner 

 and Korb,^^ and Meissner"*^ have obtained the same results. The last 

 used a simple distillation apparatus of the open model as ordinarily 

 used in laboratory work. She found that the bacteriophage passed over 

 in two experiments out of eight when she took no precautions to prevent 

 the passing over of droplets. It was only necessary to suspend a small 

 disc of rubber over the opening of the tube emitting the vapor to prevent 

 entirely the passage of the droplets and of the bacteriophage corpuscles 

 as well. This offers additional proof that the droplets are in reality 

 the vehicles which carry over the corpuscles. 



Sedimentation 



The following experiments^^'^ show that the bacteriophage corpuscles 

 sediment to the bottom of a vessel. This deposition occurs either 

 spontaneously with the passage of time, or mechanically, through 

 centrifugation. 



A suspension of an anti-dysentery bacteriophage is filtered through a 

 bougie and allowed to stand without moving in a cupboard for eleven 

 months. At the end of this time, specimens from the surface and from 

 the bottom of the tube are taken with capillary pipettes. 



The count of the superficial layers showed 280,000,000 per cubic 

 centimeter. 



The count of the deeper layers showed 2,900,000,000 per cubic centi- 

 meter. 



That the corpuscles can be sedimented, although incompletely, by 

 centrifugation at very high speed is shown by the following. 



Twenty-five cubic centimeters of the bacteriophage (antidysentery) 

 are filtered through a bougie and are centrifuged in a Jouan apparatus 

 for 30 minutes at 12,000 revolutions per minute. Counts show the 

 following: 



per cubic 

 centimeter 



Before centrifugation 1,750,000,000 



. .^ ^ .. ^. /Surface 50,000,000 



After centrifugationjg^^^^^ 3,700,000,000 



These results have been contradicted by a number of authors, but 

 nevertheless I am still convinced of their accuracy, for in recent experi- 



