BACTERIOPHAGOTJS ULTRAMICROBE 115 



It is only since the discovery of the bacteriophage that it has 

 been possible to affirm that each ultramicrobe is a material mass 

 capable of multiplication in the form of like masses. Thanks to 

 it, our ideas regarding viruses have acquired some degree of pre- 

 cision. The study of the bacteriophage by physicists would 

 offer findings of extreme interest, for it is the only virus demon- 

 strated by experiment to exist in particulate form, and with this 

 alone is it actually possible to fix dimensions, thanks to the possi- 

 bility of recognizing the number of elements present in a liquid. 



VITALITY 



The bacteriophagous ultramicrobe is extremely resistant toward 

 the majority of destructive agents, a property which it shares, 

 moreover, with other ultramicrobes. 



The vitality is very great. Filtrates or cultures containing 

 the bacteriophage are still active after six years when preserved 

 in a sealed tube. However, not all of the germs present in a 

 culture show the same degree of resistance. After preservation 

 for four years a culture which originally contained two thousand 

 million ultramicrobes per cubic centimeter contains only about 

 one hundred millions of living organisms. Such vitality is not 

 exceptional, for certain bacteria, not spore-forming, show a re- 

 sistance of the same order. For example, cultures of B. coli are 

 still cultivable after ten years or so, and here also the different 

 bacilli of a culture do not offer the same resistance, for the num- 

 ber of those which survive becomes smaller and smaller with 

 time. 



If a culture of the bacteriophage is allowed to evaporate slowly 

 at room temperature it is found that living germs may be found 

 in the few drops of syrupy fluid remaining in the bottom of the 

 tube. Indeed, certain bacteria act in the same way. On the 

 contrary, living organisms are no longer to be found after twelve 

 months in glucose bouillon cultures, although they may still be 

 alive in lactose bouillon. 



In fecal material preserved at room temperature in sealed 

 tubes for thirty-four months (September, 1915, to July, 1918) 

 one may recover the living bacteriophage, as active as at the 

 beginning. This experiment has been performed successfully 

 with four specimens of feces from convalescent cases of dysentery. 



