MOVING PHOTOMICROGRAPHY— KAZEEFP 335 



phenomenon was verified by other scholars for different microbes. 

 Bordet has shown that these bacterial agglutinins resist heating at 

 56° C. The agglutinins are thus independent of alexin. It should be 

 observed that the agglutinated microbes are not dead; sown on the 

 culture media, they grow like normal microbes. 



The organism can thus defend itself against the invading microbes 

 by phagocytic action and by the elaboration of properties such as the 

 sensibilisatrices, bacteriolysins, agglutinins, precipitins, etc. These 

 substances may be united under the term antibodies. Other experi- 

 ments have proved that only the substances which are of a protein 

 nature, for example, those which are derived from animals or plants 

 (cells, red blood corpuscles, milk, albumins, serums, microbes, etc.) 

 provoke this elaboration of the antibodies. All the substances capable 

 of inciting the formation of these antibodies are grouped under the 

 term antigens. 



BACTERIOPHAGE 



There exists another principle of defense, mysterious because it 

 remains sealed against our natural means of microscopic investigation 

 and because agreement cannot be reached regarding its nature: It is 

 bacteriophage. 



The definition of it as given by Dr. D'Herelle, who discovered it, 

 follows: 



The lytic principle, which I term Bacteriophagum intestinale or Bacteriophage is 

 a particle that multiplies at the expense of the excretions of bacteria, capable in 

 consequence of assimilation, which is indefinitely cultivable in series, in vitro, in 

 its filterable form. 



The bacteriophage is cultivable Uke the microbes but it only de- 

 velops at the expense of living microbes. Sown in a culture of 

 microbes, it provokes the clearing up of the cultures in liquid media 

 and the formation of clear expanses in the cultures on solid media, 

 phenomena that prove its power of bacterial destruction. 



Its bactericidal action is manifested on a great number of microbes. 

 For example, the Shiga dysentery bacillus, submitted at 37° during 

 three-quarters of an hour to the action of the bacteriophage, shows a 

 bad color; at the end of an hour of action, there may be found only 

 granulations, residue of the microbian action. After 10 hours these 

 granulations disappear and the bouillon becomes completely clear. 



According to D'Herelle, the presence of the bacteriophage in the 

 organism is manifested especially at the moment of convalescence. 

 It resists heating at 75° and can be conserved in active culture for a 

 long time. D'Herelle considers it an ultramicroscopic organism spe- 

 cifically pathogenic toward living microbes. In other words, the 

 bacteriophage has the relation to the microbes that the microbes have 

 to the animal organism. 



