292 rHILOSOPHICAL ^'0TE3 ON 



though egg-shaped, cells. They are functionally different from the 

 cells of the Chenopodhim leaf, but essentially the same thing. 

 By-and-bye they are fertilized, and begin to attract actively the 

 vascular tissue, which their active function needs, and instead of 

 decaying they grow into seed-ljuds. We might call those o'vular 

 trichomes, and these trichomie ovules. The Chenopodium cells 

 may be regarded as atrophied ovules, functioning as hairSy but 

 possibly, under certain circumstances, like the glandular hairs of 

 Drosera, they may revert to an ovular function and bud out into 

 branches reproducing the parent plant. 



Again, to repeat what I have already stated elsewhere, Strasliurger 

 and Hillhouse, p. 254rt, say that the conceptacles of Fucus vesicu- 

 losus are pear-shaped cavities communicating with the exterior by 

 an opening. The structures radially arranged in this cavity are 

 sterile hairs, which remain unbranched, and others, much like 

 tliese in structure, but copiously branched, bear male sexual organs, 

 the antheridia. *' The antheridia are unicellular branches of 

 these hairs, of an elongated ellipsoidal form, and having abundant 



contents " " Between the sterile and fertile hairs are the 



female sexual organs, the oogonia,* each containing eight eggs or 

 oospheres." 



Here we have simple sterile hairs, mixed up with branched 

 fertile hairs, the nourishment and size of the cavity probably not 

 being enough to make all grow into fertile hairs, so that some, 

 for these reasons, and also from heredity, remain atrophied, much 

 as do many of the ovules of orchids for want of fertilization and 

 sustenance. Any organ, it appears, may be reducible, hy atrophy, 

 to a simple trichome or hair. 



The hair when worked out to its algal origin is seen to l)e a 

 reproductive organ. If we take, for instance, Cj/7nopolia barhatay 

 a calcareous alga (Fig. 124), we find that its stem is covered with 

 rcpro<luctive hairs, a portion of which is given in this figure. If 

 these primitive reproductive organs became^ partially ati-ophied 

 during the evolution of more complex organs, it is conceivable that 

 traces of them might remain on the bark of the stem and midribs, 

 &c., such as Ave find in the moss-rose, AilantJiKS (/landulosa, and 

 many other plants, in the form of glandular hairs. Indeed, in this 



* Which oogonia Bower regards as metamorphnsed hairs. 



