Mode of Inheritance of Adaptive Characters. 69 



opinion of some of these authorities on breeding, that domin- 

 ance is usually with the phylogenetically older character. 

 Should the dominance be shown to have some connection 

 with the adaptation of the individual to its surroundings, 

 it should be brought about by some form of natural selection. 

 Although the theory that the properties of the germ cells 

 are directly derived from those of the soma, has been under- 

 mined by the theory of the continuity of the germ cells, a 

 possibility of some direct or indirect mode of transmission of 

 the properties acquired by the body in reacting to its sur- 

 roundings, has, to some scientists, ever been a necessity. 

 Darwin was strongly of this opinion, and put forward his 

 theory of pangenesis as a possible method of explaining how 

 it could be brought about. Then Weismann's theory of the 

 germ plasm arose, which completely negatived all inherit- 

 ance of adaptive qualities; and this led to much division 

 of opinion between those who did and those who did not 

 consider this method of transmission a necessity of organic 

 development. 



Since then the work of embryologists, and the experi- 

 ments of breeders, have gradually strengthened, if not con- 

 clusively proved, a continuity of the germ cells, and yet the 

 faith in some method of inheritance of adaptive qualities, 

 either direct or indirect, has not abated, and indeed may 

 be said to have gained ground. The following passages, 

 taken from an abstract of a paper by Dr Beard, may here be 

 quoted (7). 



In this abstract he gives what he calls his " Understudy 

 Theory of Heredity," set up by the author as one result 

 of the discovery of a morphological continuity of germ cells. 

 After some observations, he remarks : " For various reasons 

 every egg or sperm must be regarded as containing one 

 complete set of all the characters or qualities necessary to 

 form an individual of the species. At fertilisation two sets 

 of these are somewhat loosely joined together. In the de- 

 veloping embryo only one complete set of characters is made 

 use of, and, while the other corresponding qualities remain 

 more or less dormant in its cells, that set or pack actually 

 employed may be made up of any characters taken from 



