(J Cunningham, Unisexual Inheritance. 



organ or not. Again the selectionist merely assumes that the required 

 variation occurred in the germ, and gave rise to the observed pheno- 

 mena in development. It is difficult to see how selection can be made 

 to assist in the explanation of the annual recrescence of antlers, for 

 permanent antlers would have been equally effective as weapons. It 

 may be urged that antlers once formed do not grow, but it is not 

 evident that either the periodical renewal or the characteristic branching 

 give to antlers any superiority as weapons over the permanent horns 

 of antelopes, and cattle. 



It may be fully granted that, since the growth and periodical 

 renewal of the antlers take place in existing stags as a hereditary 

 and constitutional process, independent of all exciting causes except 

 the functional activity of the testes, there must be something in the 

 constitution of the ovum from which a stag is developed, which Deter- 

 mines" all these peculiarities in the antlers. The fertilised ovum of 

 a deer or a rabbit is to our perceptions a minute mass of protoplasm, 

 and although the two may not be exactly alike in size and other 

 respects, yet it is perfectly impossible for us to distinguish in 

 them the differences which cause one to develop into a stately stag, 

 the other into a defenceless rabbit. Yet we know that there is as 

 much difference between the two ova as between the two animals into 

 which they develop. The characters of the adult animals are not due 

 to the different food they eat, nor to differences of climate, nor even 

 to the fact that the embryo in one case is developed in tbe body 

 of female deer in the other in that of a doe rabbit: they are due 

 entirely to some peculiarities in the ova, of whose existence we are 

 certain, but of whose nature we are profoundly ignorant. 



So far there is no objection in principle to Weismann's attempt 

 to construct a theory of the mechanism of development, a theory of 

 the constitution and properties of the ovum. But when we ask whence 

 was derived this power of the stag's ovum to give rise to antlers 

 having such a marvellous history, what is the reply? Merely that 

 the properties which are in the ovum arose in the ovum. 



The hypothesis of Weismann then is that the properties of the 

 deer's ovum which cause antlers to develop were originally of the 

 same nature as the blastogenic variations which occasionally in the 

 human ovum cause the development of supernumerary fingers, or hare 

 lip, or even a double head. That such blastogenic variations occur 

 is admitted, and it may even be possible in course of time to find the 

 causes of them, but the question to be considered is whether all here- 

 ditary peculiarities are of the same kind. What evidence have we of 

 tbe observed occurrence of blastogenic variations limited to one sex, 

 and correlated with the functional activity of normal reproductive 

 organs? 



