228 BIOLOGY: GENERAL AND MEDICAL 



"The development of each being, including all the forms of 

 metamorphosis and metagenesis, depends on the presence of 

 gemmules thrown off at each period of life and on their develop- 

 ment, at a corresponding period, in union with preceding cells. 

 Such cells may be said to be fertilized by the gemmules which 

 come next in due order of development. Thus the act of ordinary 

 impregnation and the development of each part in each being are 

 closely analogous processes. The child, strictly speaking, does 

 not grow into the man, but includes germs which slowly and 

 successively become developed and form the man. 



"In the child, as well as in the adult, each part generates the 

 same part. Inheritance must be looked at as merely a form of 

 growth, like the self-division of a lowly organized unicellular 

 organism. Reversion depends on the transmission from the fore- 

 father to his descendants of dormant gemmules, which occasionally 

 become developed under certain known or unknown conditions. 

 Each animal and plant may be compared with a soil full of seeds, 

 some of which soon germinate, some lie dormant for a period, 

 whilst others perish. When we hear it said that a man carries in 

 his constitution the seeds of an inherited disease, there is much 

 truth in the expression. No other attempt, as far as I am aware, 

 has been made, imperfect as this confessedly is, to connect under 

 one point of view these several grand classes of facts. An organic 

 being is a microcosm a little universe, formed of a host of self- 

 propagating organisms, inconceivably minute and numerous as 

 the stars in heaven." 



In criticising this theory of pangenesis, Galton 1 points 

 out that though it is quite in accord with Darwin's 

 theories and fully accounts for such features as are 

 embraced in the hereditary transmission of those char- 

 acters upon which species are supposed to separate, 

 there are certain difficulties, both theoretical and prac- 

 tical, in the way of its acceptance. Thus, the gemmules 

 given off by the cells must be looked upon as of 

 colloidal nature and therefore cannot be supposed easily 

 to transfuse through membranes as their free circula- 

 tion in the body would necessitate. Being in large 

 numbers in the maternal circulation, they must easily 

 find their way into the foetal circulation, unduly im- 

 pressing the offspring with maternal material. For this 

 reason, the offspring should much more closely resemble 

 the maternal grandmother than any other progenitor, 

 which is certainly not the case. If present in the circu- 



1 " A Theory of Heredity," Jour, of the Anthropological Institute, V, London, 

 1876, p. 329. 



