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the flowers of the common primrose, and such plants are called heteromorphic, 

 because they have different forms of flowers on the same species. In the 

 primrose, in one-half of the flowers the stamens will be found at a higher 

 level and overtopping the style, whilst in the other moiety the style rises 

 considerably above the stamens. Similar forms of flowers may be seen in 

 the cowslip {Primula veris), the lungwort (Pulmonaria), and various species 

 of flax (Linum), and in the purple loosestrife {Ly thrum salicaria) no less 

 than three different lengths of stamens and styles are found. Experiments 

 have conclusively proved that full fertility in such plants can only be obtained 

 when the pollen from the stamens of a proper length is conveyed to the 

 stigmas at the right level. In tubular flowers which hang down, such as 

 numerous bell-flowers, heaths, fuchsias, &c, the style projects far beyond 

 the stamens, but the stigmatic surface being at the extreme tip, the pollen 

 would and does fall harmlessly and uselessly past it. But a volume instead 

 of a chapter might be written on these elaborate contrivances, and it may be 

 set down as a botanical axiom that nature abhors self-fertilisation. 



THE POLLEN CARRIERS. 



Having dilated at such length on the obstacles to self-impregnation, I 

 shall more briefly describe how these ditnculties are surmounted and cross- 

 fertilisation accomplished. For this purpose two agencies are employed, viz. 

 the wind and insects. Plants which are directly fertilised by the wind are 

 called Anemophilous, whilst those which are dependent on the visits of insects 

 are known as Hhtomophilous. There are several salient features which are 

 always associated with these two diverse types, and the young botanist can 

 scarcely have a more interesting field of study than to segregate and classify 

 the plants he may meet with, according as they may belong to one or other 

 of these two divisions. Anemophilous plants are remarkable for the pro- 

 duction of enormous quantities of pollen, disseminated as it is by such an 

 erratic agency, for the wind bloweth where it listeth, and a great deal of it 

 is scattered aimlessly and wasted in the air. To this cause is to be attributed 

 the so-called sulphur showers, seen in the vicinity of pine forests, and which 

 covers the ground with a yellow dust. The pollen itself is also generally 

 very dry and powdery, so as to be easily scattered, and to its wide diffusion 

 has been recently attributed the distressing ailment of hay fever, which is 

 now supposed to be caused by its irritating particles getting into the air 

 passages of the lungs and nostrils. Another characteristic feature is the 

 early blossoming of this tribe of plants, the flowers appearing before the 

 foliage, so as to avoid the interception of the pollen by the intervening 



