234 REVIEWS. 



trations of the vast amount of pollen produced by anemophi- 

 lous plants, and the great distances to which their light 

 pollen is often carried by the wind, — all these inviting topics 

 we must now pass by. 



In passing we note the remark that " the excretion of a 

 sweet liquid by glands seated outside of a flower is rarely 

 utilized as a means of cross-fertilization by the aid of in- 

 sects ; " and the sole exception alluded to is that of the bracts 

 of Marcgraviacece, But a parallel case is afforded by many 

 species of Euphorbia, and notably in a striking species culti- 

 vated in conservatories, under the name of Poinsettia. Here 

 the attraction to the eye is supplied by the intense red colora- 

 tion of ordinary leaves placed next to the inflorescence, and 

 that to the palate or tongue (if either term be allowed), by 

 a large cup-shaped gland on the side of the involucre, wdiich 

 contains or surrounds the naked and greatly simplified flowers 

 of both sexes. 



That anemophilous plants are prevailingly declinous (either 

 monoecious or dioecious) is speculatively connected with their 

 antiquity ; that they are very largely trees or shrubs is 

 because " the long life of a tree or bush permits of the separa- 

 tion of the sexes with much less risk of evil from impregna- 

 tion occasionally failing, and seeds not being produced, than 

 in the case of short-lived plants. Hence it is probably, as 

 Lecoq has remarked, that annual plants are rarely dioecious." 

 The number of anemophilous species is comparatively small, 

 but that of individuals of the species strikingly large, so that 

 they form of themselves, in cold and temperate regions, 

 where plant-fertilizing insects are fewer, either vast forests, 

 as of Coniferce.^ Birches, Beeches, etc., or meadows and glades, 

 as of Grasses, Sedges, and Kushes. Being thus either neces- 

 sarily or prevailingly cross-fertilizable and gregarious, it is 

 not wonderful that they should hold their own unchanged in 

 various parts of the world. Still their advantage is gained 

 at the expense of the production of an enormous superfluity 

 of pollen, a costly product ; and, when dioecious, half the in- 

 dividuals produce no seed. Hermaphroditism with dicho- 

 gamy, or some equivalent, and transportation by an appeal 



