HISTORICAL SKETCH 3 



covery in the description and classification of the lower or- 

 ganisms. He succeeded in arranging in order the confused 

 throng of microscopic beings. 



Miiller divided the bacteria into two classes, Monas and 

 Vibrio, names which are still used. The species of the genus 

 Monas, only incompletely described, can scarcely be recog- 

 nized ; two of the ten species which he includes are evidently 

 short bacteria. In the genus Vibrio he described thirty-one 

 species, six of which are undoubtedly true bacteria. 



Lamarck 2 , Bruguiere 3 , and Bory de Saint-Vincent 4 

 confined themselves to reproducing, either intact or with 

 slight modifications, the principles laid down by Miiller 

 which remained as law for nearly a half century. 



Ehrenberg, using better instruments, made great pro- 

 gress in the study of microscopic life. In his great work 

 on Infusoria 5 are found results far superior to those of the 

 workers before his time. He made the new class Vibrionia 

 which he spoke of as "small filiform beings without external 

 organs, united in chains or filiform series through an incom- 

 plete spontaneous division." Since that time bacteria have 

 never drifted entirely out of sight. 



Du jar din 6 followed the ideas of Ehrenberg with only 

 slight modifications. He gave new nd interesting details 

 on the development of bacteria in different media and the 

 manner of obtaining and studying them. 



The results obtained at that time were of great import- 

 ance ; some of them were repeatedly confirmed and are still 

 to be found in the best works of today. The achromatic 

 microscope, which was being brought to perfection, allowed 



2 Lamarck. Histoire des animaux sans vertebres. Paris, 1815- 

 1819; et 2e edition par Deshayes et Milne-Edwards. Paris, 1835-1845. 



3 Bruguiere. Encyclopedie methodique. Paris, 1824. 



4 Bory de Saint-Vincent. Encyclopedie methodique. Paris, 1824. 



5 Die Infusionstierchen als vollkommene Organismen. Berlin 

 1833. 



6 Dujardin. Histoire naturelle des Zoophytes Infusoires, Paris 

 1841. 



