Regeneration and Generation 139 
also that which is capable of regenerating all three pha- 
langes; or the distal part of the second phalanx should 
contain, besides the accessory idioplasm capable of regen- 
erating the distal portions of the second phalanx and the 
whole of the third phalanx, also that which is capable of 
regenerating both the third phalanx and the entire second 
phalanx itself. Why, then, should only that accessory 
idioplasm become activated which is capable of regenerat- 
ing just the particular part cut off? 
Further, Weismann himself recognizes that when dif- 
ferent tissues and organs are cut through, “it is only the 
harmonious equipment of the cells of a definite cross sec- 
tion with groups of determinants, different but mutually 
adaptable, in accord among themselves and compliment- 
ary, that could make regeneration of the higher type pos- 
sible.” 112. But really it is not easy to conceive how this 
harmonious equipment of reserve idioplasm could be 
guaranteed in the great number of different cells of a 
complex section. 
Roux has seen so clearly this impossibility of explain- 
ing the phenomena of regeneration by preformation 
theories, that he asserts that in “direct” or “typical” gen- 
eration self-differentiation may have the preponderance 
over differentiation due to reciprocal actions among the 
parts without nevertheless entirely excluding it; but in 
regeneration, which he calls “indirect” or “atypical” 
generation, he admits that differentiation of epigenetic 
nature must necessarily prevail over preformation."® 
Weismann has rightly been unwilling to fall into the 
contradiction of imagining two different natures for two 
112Weisann: Ibid. P. 297—208. 
18Royx: Uber Mosaikarbeit usw. Anat. Hefte. P. 279—331. 
Gesamm. Abhandl. II. P. 819—870. 
