CHAPTER IV 



The Bacteriophagous Ultramicrobe 



Morphology. Viability. Susceptibility to Different Substances. Unicity 

 of the Bacteriophage. Lysins of the Bacteriophage. Opsonic Power 

 of the Lysins. 



MORPHOLOGY 



The bacteriophagous ultramicrobe is of extreme tenuity. In 

 a medium containing the bacteriophage the ultramicroscope 

 reveals only some very minute brilliant points. Probably each 

 of these points represents an ultramicrobe, particularly since 

 their abundance, in greater or lesser numbers, corresponds some- 

 what with the counts made upon agar. Its tenuity is such that 

 a medium containing several thousand million ultramicrobes 

 per cubic centimeter appears perfectly limpid. The ultramicrobe 

 is, however, resident in a definite mass, since each element is 

 deposited on agar in distinct points and this mass must be appre- 

 ciable since the ultramicrobes spontaneously sediment in the 

 course of time. 



Experiment XXX. A culture of an anti-dysentery bacteriophage is 

 filtered through a bougie and allowed to stand without moving in a cup- 

 board for eleven months. At the end of this time, specimens of the cul- 

 ture 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 centi- 

 meter. 



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

 meter. 



The ultramicrobe can be sedimented, although incompletely, 

 by centrifugation at very high speed. 



Experiment XXXI. Twenty-five cc. of the bacteriophage (antidysen- 

 tery) are filtered through a bougie and are centrifuged in a Jouan appara- 

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

 following: 



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