

372 PROVISIONAL HYPOTHESIS Chap. XXVII.. 



mental endowments and bodily powers are all inherited. Nothing 

 in the whole circuit of physiology is more wonderful. How can 

 the use or disuse of a particular limb or of the brain affect 

 a small aggregate of reproductive cells, seated in a distant part 



of the body 



the being developed 



these cells inherits the characters of either one or both 

 parents? Even an imperfect answer to this question would 

 be satisfactory. 



Sexual reproduction does not essentially differ, as we have 

 seen, from budding or self-division, and these processes graduate 

 through the repair of injuries into ordinary development and 

 growth ; it might therefore be expected that every character 

 would be as regularly transmitted by all the methods of re- 



■ 



production as by continued growth. In the chapters devoted 

 to inheritance it was shown that a multitude of newly-acquired 

 characters, whether injurious or beneficial, whether of the lowest 

 or highest vital importance, are often faithfully transmitted 

 ■frequently even when one parent alone possesses some new 

 peculiarity. It deserves especial attention that characters ap- 

 pearing at any age tend to reappear at a corresponding age. 

 We may on the whole conclude that in all cases inheritance 

 is the rule, and non-inheritance the anomaly. In some instances 

 a character is not inherited, from the conditions of life being 

 directly opposed to its development; in many instances, from 

 the conditions incessantly inducing fresh variability, as with 

 grafted fruit-trees and highly cultivated flowers. In the re- 

 maining cases the failure may be attributed to reversion, by 

 which the child resembles its grandparents or more remote pro- 



enitors, instead of its parents. 

 This principle of Ke version is the most wonderful of all the 

 attributes of Inheritance. It proves to us that the transmission 

 of a character and its development, which ordinarily go together 

 and thus escape discrimination, are distinct powers ; and these 

 powers in some cases are even antagonistic, for each acts alter- 

 nately in successive generations. Reversion is not a rare event, 

 depending on some unusual or favourable combination of circum- 

 stances, but occurs so regularly with crossed animals and plants, 

 and so frequently with uncrossed breeds, that it is evidently an 

 essential part of the principle of inheritance. We know that 





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