2 THE THEORY OF SPONTANEOUS GENERATION 



and dissolution of dead vegetable matter; the ripening of cheese ; the formation 

 of bog (iron) ore, &c. &c. 



2. Discovery of Fermentative Organisms. 



The organisms taking part in the processes of fermentation are so minute 

 that only a few can be detected, and that very imperfectly, by the unassisted eye. 

 The term microbe, introduced into the vocabulary of science by C. SEDILLOT (I.) l 

 in 1878, belongs to them of right. Their examination could not be carried on 

 anterior to the invention of appliances for observing minute bodies under high 

 powers of magnification, and therefore the inventors of the microscope deserve 

 to be held in grateful remembrance in the domain of fermentation. These were 

 Hans and Zacharias Janssen, father and son, spectacle-grinders, of Middelburg, 

 in Holland, who, about the year 1590, constructed a combination of lenses 

 which, although, of course, very imperfect when, compared with the instrument 

 of the present day, must be regarded as the first compound microscope made. 



Nevertheless, however great this step undoubtedly was, both from a theoretical 

 and practical point of view, and however fruitful it proved in results, seeing that 

 it rendered possible later discoveries in the world of the " infinitely little," and 

 especially of the fermentative organisms ; still the fact remains that the first 

 fundamental observations were made, not with the compound, but with the 

 simple microscope, which then, as now, was little more than a magnifying glass 

 or bi-convex glass lens. 



The honour of having discovered the presence of extremely small and hitherto 

 undetected organisms in putrescent and fermenting liquids belongs to another 

 native of Holland, by name ANTONY VAN LEEUWENHOEK. Born at Delft in 1632, 

 he acquired during his apprenticeship to a linen or cloth merchant in Amsterdam 

 some skill in grinding small glass lenses. Of this skill he made further use after 

 his final return to his native town, and succeeded in producing lenses capable of 

 magnifying from 40 to 100, and even to 150 times. With these he examined 

 various minute objects, and frequently, amongst others, all kinds of vegetable 

 infusions in a state of decomposition. He discovered therein sundry extremely 

 small creatures, many of them capable of motion, which he therefore regarded as 

 animals, and named from their habitat infusoria. He died in 1723. The modern 

 world has entitled him "the father of micrography," i.e. that science which treats 

 of the most minute forms of life. 



This newly-discovered field of research was at first regarded by Leeuwen- 

 hoek's successors from an almost exclusively medical standpoint, as it is a 

 natural instinct in man to try and maintain health and to prevent disease. At 

 that particular period, too, a special impetus was given to the study of medicine 

 by the ravages of the plague, which only too frequently pursued its destructive 

 course throughout Europe. 



On the other hand, the study of the phenomena of fermentation derived 

 little or no benefit from Leeuwenhoek's discovery. The first investigator whom 

 we meet with in this domain is the Viennese physician, Marcus Antonius 

 Plenciz, who in his work "Opera medico-physica," issued in 1762, applied the 

 results of Leeuwenhoek's discoveries, not only to the field of medicine, but also 

 to that of fermentation and putrefaction. In the latter connection he arrived 

 at the noteworthy conclusion that "a body undergoes putrefaction when the 

 germs of vermicular creatures begin to develop and multiply ; because these 

 animals excrete numerous precipitations consisting of volatile salts, by which 

 the liquids are rendered turbid and malodorous." 



i The Roman numerals given in brackets after the names of investigators refer to the 

 Bibliographical References forming an appendix to the second volume. 



