BACTERIA 3 



a famous French physician, belongs the honor of demonstrating 

 the latter fact. An organism was found in the blood of animals 

 suffering from anthrax by Pollender in 1849 and by Davaine in 

 1850. It was the latter, however, who demonstrated in 1863 by 

 inoculation experiments that the specific organism was the cause 

 of the anthrax. 



The brilliant researches of Pasteur may be regarded as the 

 foundation of the Science of Bacteriology ; later investigators have 

 contributed largely to placing it on the basis of an independent 

 position in natural science. A great impetus was given to the 

 study when Robert Koch invented a solid-culture medium by means 

 of which the descendants of a single cell could be studied alone. 

 This made possible the knowledge of such fundamental principles 

 as the mode of development, physiological requirements, and 

 capabilities of each species, a knowledge essential not only to a 

 proper understanding of bacteriology, but also to the practical 

 application of furthering the usefulness of such microorganisms 

 as are of benefit to mankind and of combating those which by their 

 activities produce disease. 



Several attempts have been made to provide a satisfactory 

 classification of these microscopic living cells, but as yet no one has 

 succeeded in presenting a really adequate one. This can readily 

 be understood when one realizes the minuteness of their size and 

 the consequent difficulty of determining their relation one to the 

 other. 



In addition to the organisms which may be studied by means of 

 the microscope still others exist which are so small as to be in- 

 visible with any magnification which we now possess. That 

 they exist is certain because they can be grown in mass on 

 culture media and the cultures when inoculated into susceptible 

 animals produce the characteristic disease; they are so minute 

 that they will pass through the finest porcelain filter. The group 

 is generally spoken of as Ultramicroscopic or Filtrable viruses. 



The following broad outline (after Park and Williams) serves 

 to show the relationship of those forms that are of special interest 

 in that they are able to produce disease. 



