138 Facts Compelling Us to Reject Preformation 
trolling determinants also all the determinants of the 
forearm and of the hand as accessory idioplasm, for they 
can cause the entire chain of these bones to be formed 
anew; and the cells of the radius must contain as acces- 
sory idioplasm all the determinants of the radial portion 
of the wrist, hand and fingers. 
“We can regard this theoretical requirement as quite 
realizable also, since when the whole organ commences 
to be formed, the necessary accessory idioplasm can very 
well separate from the disintegrating embryonic idio- 
plasm. We need only assume that this accessory idio- 
plasm remains henceforth inactive in the nuclear sub- 
stance of the cell until some cause for regeneration 
arises,”’ 111 
We note at once that, according to this hypothesis, 
there is no reason at all why there should be held in re- 
serve in each part of the bone only the accessory idio- 
plasm capable of regenerating the bony parts distal to 
that point, but never any other capable of regenerating a 
larger or smaller part. Each particular reserve idioplasm, 
when once it has separated itself in a given cell from the 
principal idioplasm, and been segregated in the nucleus of 
the cell itself in the latent state, will be able to preserve 
itself unaltered through many generations of cells. Con- 
sequently there must be present at any point at which a 
bone may be broken several accessory idioplasms, each 
capable of regenerating a more or less long portion of the 
bone which was broken, and perhaps also of some other 
bone. In the illustrative case cited by Weismann the sec- 
ond phalanx should contain besides the reserve idioplasm 
capable of regenerating the second and third phalanx, 
111Weismann: Das Keimplasma. P. 136—138. 
