vii.] EFFECT ON SEXUAL CELLS 73 



feature of degeneracy is seen in the ovules, etc. 

 For, while a normal ovule, say of a buttercup, 

 would consist of a central " nucleus " containing 

 the " embryo-sac " within it, and surrounded by 

 two coats, in some parasites, as the mistletoe, 

 there is nothing but a naked embryo - sac. 

 When an ovule becomes a seed, the embryo, 

 instead of having two cotyledons, a plumule 

 and a radicle, may remain arrested in the pro- 

 embryonic condition of a globular cellular body, 

 the outermost skin of the seed being a simple 

 cellular sac. Such seeds, for example, occur 

 in the broom-rape. This kind of degeneracy 

 in the reproductive system seems to be one 

 of the first conditions, for it occurs in plants 

 unsuspected of parasitism on other grounds, 

 from which true parasites have descended, as 

 e.g., winter- green, from which genus the green- 

 less Bird's-nest has probably been derived. 



The extreme degradations of parasites negative 

 Weismann's idea that any characters acquired by 

 the soma cannot affect the reproductive system ; 

 for no plants have more degraded conditions in 

 their ovules and embryos than parasites. If, 

 moreover, it be asserted that such degradations 

 as abound in these plants must be due to the 

 parasitism of each generation, we may ask 

 why it is that colourless parasites never start 

 with green leaves., as do those of the section 

 EuphrasiecB of Scrophularinece, and why do 



