Chap. XII. INHERITANCE. 445 



CHAPTER XII. 



INHERITANCE. 



WONPERFUL NATURE OP INHERITANCE — PEDIGREES OF OUR DOMESTICATED 

 ANEUALS — INHERITANCE NOT DUE TO CHANCE — TRIFLING CHARACTERS 

 TNHERITED — DISEASES INHERITED — PECULIARITIES IN THE EYE INHERITED 

 — DISEASES LN THE HORSE — LONGEVITY AND VIGOUR — ASYMMETRICAL 

 DEVIATIONS OF STRUCTURE — TOLYDACTYLISM AND REGROWTH OF SUPER- 

 NUMERARY DIGITS AFTER AMPUTATION — CASES OP SEVERAL CHILDREN 



SIMILARLY AFFECTED FROM NON - AFFECTED PARENTS WEAK AND 



FLUCTUATING INHERITANCE : IN WEEPING TREES, LN DWARFNESS, COLOUR 



OF FRUIT AND FLOWERS— COLOUR OF HORSES NON-INHERITANCE IN 



CERTAIN CASES— INHERITANCE OP STRUCTURE AND HABITS OVERBORNE 

 BY HOSTILE CONDITIONS OF LIFE, BY INCESSANTLY RECURRING VARIA- 

 BILITY, AND BY REVERSION — CONCLUSION. 



The subject of inheritance is an immense one, and has been 

 treated by many authors. One work alone, ' De l'Heredite 

 Naturelle,' by Dr. Prosper Lucas, runs to the length of 1562 

 pages. We must confine ourselves to certain points which have 

 an important bearing on the general subject of variation, both 

 with domestic and natural productions. It is obvious that a 

 variation which is not inherited throws no light on the deri- 

 vation of species, nor is of any service to man, except in the 

 case of perennial plants, which can be propagated by buds. 



If animals and plants had never been domesticated, and 

 wild ones alone had been observed, we should probably nevei 

 have heard the saying, that " like begets like." The propo 

 sition would have been as self-evident as that all the buds on 

 the same tree are alike, though neither proposition is strictly 

 true. For, as has often been remarked, probably no two 

 individuals are identically the same. All wild animals re- 

 cognise each other, which shows that there is some difference 

 between them ; and when the eye is well practised, the shep- 

 herd knows each sheep, and man can distinguish a fellow- 

 man out of millions on millions of other men. Some authors 

 have gone so far as to maintain that the i^roduction of slight 

 differences is as much a necessary function of the powers of 



