20 PATHOGENIC BACTERIA. 



wenhoek, among other things, demonstrated the conti- 

 nuity of arteries and veins through intervening capil- 

 s, thus affording ocular proof of Harvey's discovery 

 of the circulation of the blood; discovered the rotifers, 

 and also the bacteria, seeing them first in saliva. 



Although one of those who contributed to the support 

 of Redi's arguments against the spontaneous generation 

 of maggots, Leeuwenhoek involuntarily reopened the old 

 controversy about spontaneous generation by bringing 

 forward a new world, peopled by creatures of such ex- 

 treme minuteness as to suggest not only a close relation- 

 ship to the ultimate molecules of matter, but an easy 

 transition from them. Interested in Leeuwenhoek' s 

 work, Plencig of Vienna became convinced that there 

 was an undoubted connection between the microscopic 

 animals exhibited by the microscope and the origin of 

 disease, and advanced this opinion as early as 1762. 

 Unfortunately, the opinions of Plencig seem not to have 

 been accepted by others, and were soon forgotten. 



In succeeding years the development of the compound 



microscope showed these minute organisms to exist in 



such numbers that putrescent infusions, both animal and 



table, literally teemed with them, one drop of such 



a liquid furnishing a banquet for millions. 



Much hostility arose in the scientific world as years 

 went on until two schools attained prominence one 

 headed by Buffon, whose doctrine was that of "organic 

 molecules;" the other championed by Needham, whose 

 doctrine was the existence of a "vegetative force" which 

 drew the molecules together. 



Experimentation was begun and attracted much atten- 

 Aniong the pioneers was Abbe Lazzaro Spallan- 

 /.mi 1777), who filled flasks with organic infusions, 

 sealed their necks, and, after subjecting their contents 

 to the temperature of boiling water, placed them under 

 conditions favorable for the development of life, without, 

 however, being able to produce it. Spallan/ani's critics, 

 however, objected to his experiment on the ground that 



