———— er ee 
317 
birth. Even if the amputation were performed directly after 
birth, there would be the pre-natal tailed stage to be repeated. 
On the other hand, if, on account of lessened use, which 
involves a lessened blood-supply to the tail, and therefore less 
nutriment being received by it, the tail is 1 mm. shorter, the 
repetition of ontogeny by the offspring would repeat this 1 mm. 
shortness, and the continuance of the same causes would detract 
another 1mm. This would be normal development. 
The basis of Weismann’s theory is that every change 
must come from a spontaneous variation of the germ; but I 
may say that to be recognised as spontaneous a variation must 
be appreciable in immaturity, because if not manifest till 
maturity, the variation might reasonably be claimed as the 
result of environment, and its spontaneity denied. Such is the 
evidence of Ammonites. They show that the different species 
arose from variations which did not appear till maturity, and 
that these variations gradually became embryonic by the law 
of earlier inheritance. By the Weismann theory, however, we 
must suppose an infinite number of spontaneous variations, 
each one in exactly the right direction, each one making the 
particular feature manifest a little earlier and earlier than 
before in order to achieve this result. I need scarcely remark 
on the intricateness of this theory. 
I will examine some statements made against the inherit- 
ance of those acquired characters which, for the sake of 
distinction, I have called normal or developmental variations.* 
(p. 264). 
* This term was first proposed in reference to the cyclical development of 
Ammonites, which may be illustrated by the following table :— 
4 
spinous 
aaa 
3 costate costate 3 
2 striate striate 2 
Y 
1 smooth smooth 1 
This development may be varied 
in any number of ways, as for 
instance, 1, 2 2,1. 123321. 
12343234321, or 123438 
then extinct, and so on. 
Progressive 
PATSSOLSOIIOY 
