INTRODUCTION 7 



) Galton * was the first to make an attempt to improve on the 

 theory of pangenesis. In a short but suggestive essay he 

 accepted the hypothesis' of the gemmules, but rejected the 

 doctrines of their circulation through the blood, and of the 

 aggregation in the germ-cells of gemmules given off by the body- 

 cells. Now as the gemmules which have been converted into 

 body-cells are used up, it follows that the germ-cells can only 

 contain those gemmules which are left — those, out of the enor- 

 mous number contained in a germ-cell, which have not developed 

 further. For each germ-cell, as both Galton and Darwin assume, 

 contains each kind of gemmule in many modifications, originat- 

 ing from the different ancestors of the organism. The theory 

 of the origin of the germ-cells from the remains of the germ 

 mass not used up in ontogeny (' the residue of the stirp ■) has 

 been compared to, and regarded as the precursor of, the con- 

 ception of the continuity of the germ-plasm which 1 originated 

 long afterwards. A certain resemblance does, it is true, exist 

 between the two conceptions, but it will be shown in the section 

 on the continuity of the germ-plasm that the similarity is only a 

 superficial one. 



Herbert Spencer defines heredity as the capacity of every 

 plant and animal to produce other individuals of a like kind, 

 and states expressly that in this fact, which is perfectly famil- 

 iar to us, and for this reason seems to be a matter of course, 

 lies the real essence and principle of heredity, ' the phenom- 

 ena commonly referred to it being quite subordinate mani- 

 festations.' Thus the blending of the i>idrindual ^characters' 

 of the parents in the children has, as a rule, been placed in 

 the foreground in considering questions of heredity, and it has 

 been overlooked that this is quite a secondary phenomenon, — 

 imi'«ortajit no doubt in many respects, and interesting in a high 

 degree, but still only the result of a certain mode of multipli- 

 cation, i.e., sexual reproduction, and by no means an essential 

 phenomenon of heredity. Darwin recognised this distinctly, 

 (and concerned himself primarily with the theoretical explana- 

 lion of individual development (ontogeny). But the majority 

 nf writers on heredity, including Galton, have turned their 

 Nvhole attention to the blending of the qualities of the parents 



It * Francis Galton, ' A Theory of Heredity,' Juttrtial of tlie Anthropo- 

 logical Institute, 1875. 



