ADVANCE OF ZOOLOGY. 2/ 



the beginning, there could naturally be no evolu- 

 tion of form, nor any necessity for a theory of 

 Evolution. Long before Aristotle, the principle 

 of Syngenesis, or formation of the embryo by the 

 union of elements from both parents, was rightly 

 understood by Empedocles. The notion of heredi- 

 tary transmission of characters was extremely an- 

 cient, and was naturally founded upon the early 

 observed likeness of offspring to parents. Aris- 

 totle also commented upon the principles of the 

 prepotency of the characteristics of one parent 

 over the other, as well as of Atavism. 



The growth of Embryology as an objective sci- 

 ence came, of course, with the invention of micro- 

 scopic lenses. Degraff, in the discovery of the 

 ovum in 1678, Leeuwenhoek (1632-1723) in the 

 discovery of the spermatozoon, laid the foundations 

 of the science which Meckel, in 1813, an d Von Baer, 

 in 1827, built into one of the keystones of Evolu- 

 tion. Von Baer's law, that higher animals passed 

 through embryonic stages in which they resemble 

 the adult forms of lower types, was also dimly per- 

 ceived by Aristotle, but not, of course, in its vital 

 relation to Evolution. 



Aristotle also distinguished between living and 

 lifeless matter as the organic and inorganic, but in 

 common with all the Greeks, and, in fact, with all 

 zoologists up to comparatively recent times, he 

 believed in A biogenesis, or the spontaneous develop- 

 ment of livinor from lifeless matter. This belief 



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