INTRODUCTION OF THE MICROSCOPE 77 



In reference to the formation of animals within the egg, 

 Swammerdam was, as Malpighi, a believer in the pre-forma- 

 tion theory. The basis for his position on this question will 

 be set forth in the chapter on the Rise of Embryology. 



There was another question in his time upon which philos- 

 ophers and scientific men were divided, which was in reference 

 to the origin of living organisms : Does lifeless matter, some- 

 times, when submitted to heat and moisture, spring into life ? 

 Did the rats of Egypt come, as the ancients believed, from 

 the mud of the Nile, and do frogs and toads have a similar 

 origin ? Do insects spring from the dew on plants ? etc., etc. 

 The famous Redi performed his noteworthy experiments 

 when Swammerdam was twenty-eight years old, but opinion 

 was divided upon the question as to the possible spontaneous 

 origin of life, especially among the smaller animals. Upon 

 this question Swammerdam took a positive stand ; he ranged 

 himself on the side of the more scientific naturalists against 

 the spontaneous formation of life. 



ANTONY VAN LEEUWENHOEK (1632-1723) 



In Leeuwenhoek we find a composed and better-balanced 

 man. Blessed with a vigorous constitution, he lived ninety- 

 one years, and worked to the end of his life. He was born 

 in 1632, four years after Malpighi, and five before Swammer- 

 dam; they were, then, strictly speaking, contemporaries. 

 He stands in contrast with the other men in being self-taught ; 

 he did not have the advantage of a university training, and 

 apparently never had a master in scientific study. This lack 

 of systematic training shows in the desultory character of his 

 extensive observations. Impelled by the same gift of genius 

 that drove his confreres to study nature with such unexampled 

 activity, he too followed the path of an independent and 

 enthusiastic investigator. 



