408 ZOOLOGY 



ture which were independent and parallel and cUd not all fall 

 into one seriew leading from Protozoa to man. Cuvier opposed 

 the theory of evolution, and so great was his influence in France 

 that the ideas of Lamarck were neglected and almost forgotten 

 in the supremacy of the view of the immutal.)ility of species. 

 The science of embryology had its beginnings in Aristotle's 

 studies on the hen's egg, and in the revival of 1 jiological studies in 

 the seventeenth century there were not wanting those who, like 

 Malpighi, made some superficial stucUes on developing chicks; 

 but it was not until the middle of the eighteenth century that 

 serious emljrj'ological studies were made. At this time there 

 was raging a discussion as to the nature of development. On 

 the one liand it was maintained that in the egg lay the embryo 

 as we see it when the chick is hatched, onl.y it is of verj' .small 

 size. Development consists in the growing of the different 

 parts until they become ^dsible. On the other hand, it was 

 asserted that the sperm-cell contains the j'oung creature and 

 that it finds in the egg food for growth. One day a teacher in 

 German}' remarked to a l:)rilliant pupil, Caspar Friedrich "Wolffj 

 that man}' things of value would be got from a careful study 

 of the development of the hen's egg. Wolff set to work and 

 succeeded in proving that the egg is at first mthout the organs 

 of the adult, and that these are gradually formed in it. These 

 conclusions, l:)ased on careful stud}', were combated by Haller, 

 the eminent physiologist, and on account of his great authoritj' 

 he crushed, for a time, the truth ; but at the beginning of the 

 nineteenth century new studies were made by Carl Ernst von 

 Baer, who confirmed Wolff's observations, and in 1832 estab- 

 lished embryology as a separate science. During the re- 

 mainder of the century embryology almost overshadowed the 

 other sul}-sciences of zoology. In England were Huxley and 



