2 HISTORY OF MICROBIOLOGY 



that microorganisms were capable of reproduction outside of the body, 

 and that they might be conveyed from place to place by the air. 



The important role that the compound microscope has played in 

 microbiology calls for something regarding the invention of this in- 

 strument an invention which antedates Leeuwenhoek's discovery by 

 nearly 100 years. 



The first compound microscope was made by Hans Jansen and his 

 son Zaccharias, in 1590, at Middelburg, in Holland. The instrument 

 was composed of two lenses mounted in tubes of iron; a representation 

 of it, made from the original and still kept at Middelburg, is shown 

 in Fig. i. From that date the microscope gradually improved. In 

 1844 the immersion lens was introduced by Dolland. In 1870 Abbe 

 brought out the substage condenser, which still bears his name. Apo- 

 chromatic lenses and many minor improvements were introduced by 

 the firm of Zeiss about 1880. 



I 



FIG. i. Longitudinal section of a compound microscope made by Zaccharias 

 Jansen (1590). a, Microscope tube; b, objective tube; c, ocular. 



In 1786 O. F. Miiller (a Dane) first attempted to classify, according 

 to theLinnean system, the various organisms previously discovered, and 

 characterized four or five genera among them, the genus Vibrio, in 

 which, under the terms bacillus, lineola, and spirillum, we recognize 

 forms that correspond with our "bacteria." 



From the middle of the eighteenth century until well on into the 

 nineteenth, the history of bacteriology is largely the story of a con- 

 troversy between those who believed that minute living organisms, such 

 as those above referred to, were produced from inanimate substances, 

 and that their formation was spontaneous. Philosophers, poets, and 

 common people of the most enlightened nations accepted this doctrine 

 down to the eighteenth century. The hypothesis regarding this forma- 

 tion was known as that of "spontaneous generation," "heterogenesis," 

 and " abiogenesis." The opponents of this theory denied the possibility 

 of a transition from a lifeless to a living condition, and contended that 

 all life came from preexisting life a theory aphoristically summed 

 up in the phrase "omne vivum ex vivo." Such was the doctrine of 

 Biogenesis life only from life. 



