GENEOLOGICAL. 397 



lowed by many workers, — the Hertwigs, Roux, 

 Driesch, Herhst, Wilson, Morgan, Loeh, Delage, and 

 many others. The results have contributed (a) to 

 the morphological problem of cell-lineage, (b) to 

 the physiological problem of growth-conditions or 

 body-physics, (c) to the general theory of the mean- 

 ing of fertilisation and development, and (d) to our 

 hnoivledge of the influence of the environment in 

 inducing modifications. But it is too soon to appre- 

 ciate the results, some of ivhich seem mere curiosities, 

 ivhile others suggest a revolutionary change of out- 

 look. 



HEREDITY AND INHERITANCE. 



Old Problems, but a Modern Study. — Even in 

 ancient times men pondered over the resemblances 

 and differences between children and their parents, 

 and wondered as to the nature of the bond which 

 links generation to generation. But although the 

 problems are old, the precise stud}^ of them is alto- 

 gether modern, and may almost be called Darwinian. 

 For it was largely under Darwin's influence, dating 

 from the publication of the Origin of Species (1859), 

 that the scientific study of the problems of heredity 

 began. The other chief influence was the cell- 

 theory, especially that development of it which Vir- 

 chow expounded — the idea of genetic continuity. It 

 should also be remembered that the first adequate pre- 

 sentation of the facts of inheritance was published 

 about the middle of the century, namely, Traite 

 de rheredite naturelle (1847-1850), by Prosper 

 Lucas, which furnished a useful basis for more crit- 

 ical enquiry. 



