SCIENCE AND REVOLUTION 



opened up entirely new fields of study, and has 

 become one of the most revolutionary aids in evo- 

 lution, the microscope. It developed out of the 

 magnifying glass, and came into use as a scien- 

 tific instrument about the beginning of the I7th 

 century. Francesco Stelluti is regarded as the 

 first who made its use known to science. It be- 

 came especially effective in the hands of Mal- 

 pighi and Leeuwenhoek. Malpighi, in the latter 

 half of the i/th century, published a complete 

 anatomy of the silk-worm and studied the devel- 

 opment of the chicken in the egg. Leeuwenhoek 

 discovered the blood corpuscles and described the 

 active elements in the semen of male animals. 

 After these scientists came an able corps of in- 

 vestigators and used the microscope to good ef- 

 fect in laying the foundation for an understand- 

 ing of the individual development (ontogeny) of 

 beings. From ontogeny to phytogeny, that is to 

 say to the development of species, genera, classes, 

 families, races, was but a logical step, which was 

 made in the iQth century as soon as the material 

 premises for it had developed. 



But in the i/th and :8th centuries, the micro- 

 scopical revelations " fell flat." This was mainly 

 due to the prevailing theological conception of 

 nature and to the lack of interrelation between 



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