RELATIVE INFLUENCE OF PARENTS. 221 



M. Girou believed that the relative age and vigor 

 of the parents determined their relative influence in 

 moulding the characters of their offspring, and Stone- 

 henge, in the paragraph above quoted, appears to be 

 inclined to accept the theory as at least a plausible 

 one. "When all other conditions are equal, it may be 

 true that the relative strength of constitution and 

 physical vigor of the parents may, to some extent, 

 determine their relative influence upon the dominant 

 characters of their offspring, but there is no evidence 

 that such influence is sufficiently intense to counteract 

 or overcome, in all cases, the other causes of heredi- 

 tary transmission. I have frequently observed in- 

 stances of animals decidedly deficient in strength and 

 vigor that were prepotent, even when coupled with 

 those that were remarkable for their high constitu- 

 tional development. 



It cannot be doubted, however, that in cases of 

 marked immaturity, or of an impaired condition of 

 the system from extreme old age, the powers of trans- 

 mission are less strongly marked than they are in the 

 meridian of health and development ; but these are 

 extreme cases, that cannot be relied upon as indicating 

 the normal laws of the function of reproduction. 



The excessive use of the male impairs his powers 

 of procreation, and undoubtedly diminishes the pa- 

 tency with which he transmits his qualities. 1 



"When there is no marked prepotency on the part 

 of either parent, the male offspring frequently resem- 

 ble the father and the female resemble the mother. 3 



1 " Massachusetts Agricultural Report," 1860, p. 172. 



2 Colin's "Physiologic comparee," vol. ii., p. 635; Journal of tlw 



