176 ACQUIRED CHARACTERS sec. 



be transmitted from the parents to the children . . . but the 

 ancestors possessed all these peculiarities by virtue of the 

 properties of their germs." 



What agencies, then, must be asked, in reply, have first 

 introduced new peculiarities into the ancestral series ? By 

 what means have quite new characters arisen at all in organic 

 beinfjs ? Sexual combination could not oricrinate them : it 

 could only work from tlie beginning with what already 

 existed, was already present. 



If I understand Weismann aright, the variability inherited 

 by the germ-plasm from unicellular ancestors is supposed to 

 have created these innovations. But such an assumption, 

 it seems to me, is purely hypothetical. It stands entirely 

 without proof, and finds its support only in the explanation 

 of portrait -like inheritance and reversion which is hypo- 

 thetically possible by its aid. 



In opposition to this assumption I believe I can appeal to facts 

 even with regard to the inheritance of injuries and diseases. 



That injuries, when continued for an extremely long time, 

 may be inherited is proved to my mind by atrophied 

 (rudimentary) organs. The degeneration of these organs 

 depends incontestably on disuse : in consequence of disuse the 

 blood -supply is diminished, in consequence of the decrease 

 of nutrition degeneration takes place. If we consider tlie 

 course of gradual degeneration, e.g. of the tail as it must have 

 taken place in the higher mammals, to have proceeded in 

 this purely physiological manner from the tip towards the 

 root, the process is much the same as if the tip of the tail 

 had been in many successive generations amputated, and the 

 shortening had been inherited, and then the shorter tail thus 

 acquired had been farther sliortened artificially, and so on. 

 In any case in the degeneration of the tail an acquired 

 character has been inherited by the offspring, a character 



