202 A STUDY IN HEREDITY 



APPENDIX C 



The human body, like that of all the higher plants and animals, 

 is a cell community. The cells are mostly adherent, and all 

 have descended from a common ancestor, the fertilised ovum ; 

 but in a very real sense every cell is a distinct and separate living 

 entity, a unicellular animal. Blood-cells are free, germ-cells are 

 purely parasitic, skin-cells have often been transplanted ; there is 

 little doubt that had we the requisite skill it would be possible to 

 transplant every other kind of cell. No single cell in the body 

 is the offspring of any other co-existing cell or group of cells ; but 

 every cell is derived from a pre-existing cell. Omnis cellula e 

 cellula. The whole cell-community is separable into two distinct, 

 but very unequal parts ; into germ-cells, and systemic (somatic) 

 cells. To the former belong the function of continuing the 

 race, to the latter the function of protecting the all-important 

 germ-cells. 



A few years ago it was universally believed that acquired 

 characters were transmissible. It was thought that changes in 

 body and mind — caused by exercise, disease, accident, or what 

 not — affected the germ-cells in such a special manner, that the 

 traits the parent acquired tended to reappear as inborn characters 

 in the child. At the present day the majority of those who have 

 given real scientific attention to the question believe the contrary. 

 The problem is of obvious importance to medical men, who, 

 however, as a body have curiously neglected it. Before beginning 

 its discussion it is necessary to define a couple of terms, the loose 

 use of which has resulted in endless confusion. 



An inborn character may be defined as one which results in 

 the individual from the constitution of the germ-cell (or pair of 



