Heredity. 



evident in the general dimensions of the brain, the principal 

 organ of that system ; it is very often apparent in the size, and 

 even in the form, of the cerebral convolutions. This fact was 

 observed by Gall, who thereby accounted for the transmission of 

 mental faculties. We need not here dwell upon this point, for we 

 shall have frequent occasion to revert to it in the course of the 

 present work. 



Heredity of the internal elements occurs in the fluids of 

 the organism, as well as in the solid parts : the blood is more 

 abundant in some families than in others, and this superabundance 

 transmits, or may transmit, to the members of such families, a pre- 

 disposition to apoplexy, hemorrhage, and inflammation. Thus there 

 exists in some families such a liability to hemorrhage that even 

 the prick of a pin may cause in them a flow of blood that 

 cannot be checked. The same may be said with regard to the 

 bile and the lymph. 



Nor is it merely, as might be supposed, the structure, whether 

 internal or external, that is thus transmissible ; some quite 

 peculiar characteristics of the mode of existence pass from parent 

 to child. Heredity governs the subordinate no less than the domi- 

 nant characteristics. Thus fecundity, length of life, and those 

 purely personal characteristics which physicians call idiosyncrasies, 

 are hereditarily transmitted. A few facts will confirm this. 



There is no doubt of the influence of heredity on the repro- 

 ductive power. Some families are noted for their fecundity, and 

 this fecundity descends either through the father or through the 

 mother. 



A mother gave birth to twenty-four children, among them five 

 girls, who in turn gave birth to forty-six children in all. The 

 daughter of this woman's son, while still young, was brought to bed 

 with her sixteenth child. (Girou.) The sons, daughters, and grand- 

 children of a couple who were the parents of nineteen children 

 were nearly all gifted, says Lucas, with the same fecundity. 



Several families belonging to the old French nobility possessed 

 extraordinary powers of propagation. Anne de Montmorency 

 (who when over seventy-five years of age was still able, at the 

 battle of St. Denis, to break with his sword the teeth of the 

 Scotch soldier who gave him his death-blow) was the father of 



