2G8 THE INDUCTIONS OF BIOLOGY. 



slightly but greatly. Just as, during the evolution of an or 

 ganism, the physiological units derived from the two parents 

 tend to segregate, and produce likeness to the male parent in 

 this feature and to the female parent in that ; so, during the 

 formation of reproductive cells by such organism, there will 

 arise in one cell a predominance of the physiological units 

 derived from one parent, and in another cell a predominance 

 of the physiological units derived from the other parent. The 

 instability of the homogeneous forbids us to assume an even 

 distribution of the two orders of units in all the reproductive 

 cells. And inequalities once arising among them, must tend 

 ever to become more marked ; since, wherever units of a 

 given order have begun to segregate, the process of differenti- 

 ation and integration tends to segregate them more and more. 

 Thus, then, every fertilized germ, besides containing different 

 amounts of the two parental influences, will contain different 

 kinds of influences this having received a marked impress 

 from one maternal or paternal ancestor, and that from an- 

 other. 



Here, then, we have a clue to the multiplied variations, and 

 sometimes extreme variations, that arise in races which have 

 once begun to vary. Amid countless different combinations 

 of units derived from parents, and through them from ances- 

 tors, immediate and remote amid the various conflicts in 

 their slightly-different polarities, opposing and conspiring 

 with each other in all ways and degrees ; there will from 

 time to time arise special proportions causing special devi- 

 ations. From the general law of probabilities it is inferable, 

 that while these involved influences, derived from many pro- 

 genitors, must, on the average of cases, obscure and partially 

 neutralize one another ; there must occasionally result such 

 combinations of them as will produce considerable divergences 

 from average structures ; and at rare intervals, such com- 

 binations as will produce very marked divergences. There is 

 thus a correspondence between the inferable results, and tlnj 

 results as habitually witnessed. 



