264 



CAUSES OF VARIABILITY. 



Chap. XXII. 







the womb. 32 This view is evidently not applicable to the lower 

 animals, which lay unimpregnated eggs, or to plants. Dr. William 

 Hunter, in the last century, told my father that during manv 

 years every woman in a large London Lying-in Hospital was 

 asked before her confinement whether anything had specially 

 affected her mind, and the answer was written down ; and it 

 happened that in no one instance could a coincidence be de- 

 tected between the woman's answer and any abnormal structure • 

 but when she knew the nature of the structure, she frequently 

 suggested some fresh cause. The belief in the power of the 

 mother's imagination may perhaps have arisen from the children 



so 



of a second marriage resembling the previous father, as certainly 

 sometimes occurs, in accordance with the facts given in the 

 eleventh chapter. 



Crossing 



Cause of Variability 



In 



chapter it was stated that Pallas 33 and a few other 



ly part of this 



that variability is wholly due 



If this means 



that new characters never spontaneously appear in our domestic 

 races, but that they are all directly derived from certain aboriginal 

 species, the doctrine is little less than absurd; for it implies 

 that animals like Italian greyhounds, pug-dogs, bull-dogs, pouter 

 and fantail pigeons, &c, were able to exist in a state of nature. 

 But the doctrine may mean something widely different, namely, 

 that the crossing of distinct species is the sole cause of the first 

 appearance of new characters, and that without this aid man could 

 not have formed his various breeds. As, however, new characters 

 have appeared in certain cases by bud- variation, we may conclude 

 with certainty that crossing is not necessary for variability. It is, 

 moreover, almost certain that the breeds of various animals, such as 

 of the rabbit, pigeon, duck, &c, and the varieties of several plants, 

 are the modified descendants of a single wild species. Neverthe- 

 less, it is probable that the crossing of two forms, when one or 

 both have long been domesticated or cultivated, adds to the varia- 

 bility of the offspring, independently of the commingling of the 

 characters derived from the two parent-forms ; and this implies 



32 Mtiller has conclusively argued 

 against this belief, 'Elements of 

 Phys.,' Eng. translat., vol. ii., 1842, 



p. 1405. 



33 ' Act. Acad. St. Petersburg,' 1 780, 

 part ii. p. 84, &c. 



