54 THE RIDDLE OF THE UNIVERSE. 



survey and discussion of the most important pheno- 

 mena. Let us first cast an historical glance at the older 

 ontogeny, 1 and the theory of preformation which is 

 connected with it. 



The classical works of Aristotle, the many-sided 

 " father of science," are the oldest known scientific 

 sources of embryology, as we found them to be for 

 comparative anatomy. Not only in his great natural 

 history, but also in a small special work, Five Books 

 on the Generation and Development of Animals, the 

 great philosopher gives us a host of interesting facts, 

 adding many observations on their significance ; it 

 was not until our own days that many of them were 

 fully appreciated, and, indeed, we may say, discovered 

 afresh. Naturally, many fables and errors are mixed 

 up with them ; it was all that was known at that time 

 of the hidden growth of the human germ. Yet during 

 the long space of the next two thousand years the 

 slumbering science made no further progress. It was 

 not until the commencement of the seventeenth 

 century that there was a renewal of activity. In 1600 

 the Italian anatomist, Fabricius ab Aquapendente, 

 published at Padua the first pictures and descriptions 

 of the embryos of man and some of the higher 

 animals ; in 1687 the famous Marcello Malpighi of 

 Bologna, a distinguished pioneer alike in zoology and 

 botany, published the first consistent exposition of the 

 growth of the chick in the hatched egg. 



All these older scientists were possessed with the 

 idea that the complete body, with all its parts, was 

 already contained in the ovum of animals, only it was so 



1 Ontogeny describes the formation of the individual ; phyloyeny the 

 genesis of a species or larger group ; bioyeny the development of life in 

 either sense. 



