HEREDITY AND " ARRANGEMENT ' 



have us believe, why is it that a duck does not 

 occasionally emerge from a hen's egg ? Surely 

 this is a miraculum, a thing to be wondered at, 

 yet so common that it goes unnoticed, like many 

 other wonderful things which are also matters 

 of common everyday occurrence, such as the 

 spinning of the earth on its own axis and its 

 course round the sun and through the heavens. 

 If we pursue this question further we shall 

 begin to remember that creatures more nearly 

 related to one another also " breed true." The 

 hen and the duck are both birds, but they are 

 not so nearly allied to one another as the lion and 

 the tiger, both of which are Felidaz, or cats. Yet 

 no one ever expects that a tiger will be born of a 

 lioness, or vice versa. Further, the pug and the 

 greyhound are both of them dogs : the name 

 canis domesticus applies to both, and one would 

 be distinguished from the other in a scientific 

 list as " Var. (i.e. variety) ' pug,' ' or " Var. 

 ' greyhound.' ' Yet one can imagine the surprise 

 of a breeder if a greyhound was born in his care- 

 fully selected and guarded kennel of pugs. In a 

 word, not only species, but varieties do tend to 

 breed true ; the child does resemble its parent 

 or parents. No doubt the resemblance is not 

 absolute : there is variation as well as inherit- 

 ance. Sometimes the variation may be recog- 

 nised as a feature possessed by a grandparent or 

 even by some collateral relative such as an uncle 

 or great-uncle ; sometimes this may not be the 

 case, though the non-recognition of the likeness 

 does not in any way preclude the possibility that 



