THE HISTORY OF ZOOLOGY 





by the nutriment stored in the ovum. The theory of preforma- 

 tion led at once to a rather incomprehensible conclusion, 

 each ovum or spermatozoon must not only contain the adult in 

 miniature, but within this the model of the next generation, and 

 that of the succeeding, and soon ad infinitum. 



During all this time the theory of abiogenesis, or the sponta- 

 neous generation of living things from lifeless or inorganic 

 matter, was pretty generally believed; it was the Italian, Redi 

 (1626-1698), who first gave a foundation of fact for the opposite 

 theory of biogenesis, that living matter arises only from living 

 matter. He showed by experiment that the maggots found in 

 decaying meat were developed from the eggs which flies had 

 deposited there, and hence did not arise spontaneously as was 

 previously supposed. The theory of spontaneous generation 

 did not die, however, until well along in the nineteenth century. 

 It was in the latter half of the seventeenth century that the 

 word "cell" was first used; two English botanists, Hooke and 

 Grew, applied it to little cavities they found in vegetable tissue, 

 and Malpighi described structures which we should call "cells." 



The last great work of the seventeenth century was the 

 " Synopsis Methodica Animalium " of the Englishman, Ray, 

 published in 1693. It was an attempt at the classification of 

 animals on the basis of structure, and, though a great advance 

 in this respect, it was unfortunate in following closely the classi- 

 fication of Aristotle. Ray, however, was the first to grasp the 

 conception of species, and thus advanced one step nearer to 

 the goal, which was finally reached by Linnaeus in the next 

 century. 



Finally, we should note in this century the natural phi! 

 phers. The Englishman, Bacon (1 561-1626), recognized the 

 variation in organisms, and appears to have entertained a gen- 

 eral conception of organic evolution. Descartes (1 596-1650), 

 the French philosopher, believed all things to have developed 

 according to natural laws, rather than by sudden acts of special 

 creation, the prevalent theory of that day. But the German, 

 Leibnitz (1646-1716), was the most outspoken in his belief con- 

 cerning the fundamental relationship between animals. He 

 says: "All natural orders of beings present but a single chain, 

 in which the different classes of animals, like so many rings, 



