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plumosums we can call to mind, but outside these there is 

 a considerable number of plumose forms so called from 

 their beautiful feathery character, which is, however, due 

 rather to abnormal subdivision than to actual extra leafi- 

 ness, and upon these varieties spores are engendered, in 

 some cases rarely and in others constantly, though never 

 in the same abundance as with the normal forms. Thus in 

 the wonderful range of plumose Polystichnms, several have 

 been reputed barren but erroneously, since instead of easily 

 visible spore heaps, a careful examination with a strong 

 lens has disclosed the existence of solitary sporangia or 

 spore pods. It is thus with P. ang. pi. Pateyii and that 

 beautiful form of P. aculeaium known as P. ac. pnlchevvimum. 

 In this connection there is no doubt that abnormal seasonal 

 conditions may induce fertility only at rare intervals, and 

 thus confirm a wrong impression as to complete infertility. 

 All the plumose Athyria known to us bear spores, and in 

 view of the principle above enunciated that extra leafiness 

 is at the expense of the fruit, a familiar axiom with fruit 

 growers proper, it is a peculiar fact that some of the most 

 plumose Athyria not only bear spores, it is true, in a some- 

 what imperfect way as regards the sorus formation, but also 

 produce numerous bulbils associated with them. It is, 

 however, conceivable that bulbils, despite their larger size, 

 do not tax the vital vigour of the plant so heavily as spore 

 heaps proper, and are the result of a check in the production 

 of such, and a transmutation of the diverted energy. The 

 superficial area of a plumose frond of this description is 

 also much greater than that of a normal frond, and this 

 naturally means extra chlorophyllic action, which may 

 serve as an additional vegetative stimulus. None of the 

 perfectly barren plumosums bear crests or terminal tassels, 

 but there are numerous examples of tasselled plumosums 

 of the partially fertile kind, and it has been found that 

 uncrested wild finds of this type have yielded finely crested 

 progeny from their spores under conditions which preclude 

 the idea of crossing with crested forms. The study of the 



