PRESENT ASPECTS OF EVOLUTION 297 



A special theory of heredity, pangenesis, has been 

 accepted by many of the Neo - Lamarckian school. 

 The theory of pangenesis, as propounded by Mr. Dar- 

 win, may be very briefly stated as follows : The cells 

 in all parts of the body are continually throwing off 

 germinal particles, or "gemmules." These become 

 scattered through the body, grow, and multiply by di- 

 yision. On account of mutual attraction they unite in 

 the reproductive glands to form eggs or spermatozoa. 

 The germ-cells are thus the bearers of heredity be- 

 cause they contain samples, so to speak, of all the or- 

 gans of the body. 



In heredity, according to "Weismann's theory, the 

 egg is the centre of control, the continuous germ-plasm 

 the source of all transmitted changes; according to 

 Darwin's theory, the body is the source, and the egg 

 is derived in great part at least from it. If you put 

 to the two the time-honored question, T^Tiich is first, 

 the owl or the egg ? Weismann would announce, with 

 emphasis. The egg ; Darwin would say, The owl. One 

 proposition is the converse of the other, and most 

 facts accord almost equally well with both theories. 



In any family, devoted for generations to literary 

 or artistic pursiiits, the children show, as a rule, an 

 aptitude for such pursuits not manifested by those of 

 other families. According to the Neo-Lamarckian 

 view, this inherited aptitude is to a certain extent the 

 result of the constant exercise of these faculties 

 through a series of generations. The active efforts 

 and voluntary disposition of the parents have given an 

 increased predisposition to the child. " Quite the re- 

 verse," says Weismann, " the increase of an organ in 

 the course of generations does not depend upon the 



