3 



and not the spores of the mature plant which correspond to 

 pollen-grains. Even in the Selaginella, which has sexual 

 differentiation in its microspores and macrospores, the micro- 

 spores give origin still to true antherozoids requiring the 

 intervention of water. Apart, then, from the valid mark 

 involved in the distinction between Flowering and Flowerless 

 plants, Phanerogams and Cryptogams may also be accurately 

 described as air-fertilised and water-fertilised, in doing which 

 we indicate a gap which no theory can bridge over. But 

 when we have thus got our first great division of Cryptogams, 

 we do not know what to do with it. It is, in fact, an un- 

 manageable aggregate of groups separated from each other by 

 such tremendous intervals as, for instance, that between the 

 Diatom and the Tree-fern. The botanist is obliged to treat it 

 as the zoologist has treated the cognate term Invertebrate, 

 that is, to break it up into more natural series. It is a mere 

 question of names whether these should be called sub-kingdoms 

 or not. As to their independent value and wide divergence 

 there is no difference of opinion. Provisionally we may 

 establish three of these sub-kingdoms, the Thallophytes, 

 Muscinece, and Pteridophytes, or, speaking roughly, the Algal 

 type, the Moss type, and the Fern type. First comes the 

 Thallopliytes, including the Algce, Fungi, and Lichens, the 

 Oharacece being considered' as Algce in deference to the pre- 

 ponderance of authority. 



Perhaps no other division of plants includes such vast 

 diversity in form, size, and mode of reproduction. It links 

 the minims of the vegetable world, the Diatoms, Micro-fungi, 

 and Oscillatoriacece, with the huge kelp of the Pacific Ocean, 

 one of the longest stems in the present epoch. But they all 

 agree in consisting of cellular tissue to the exclusion of fibro- 

 vascular bundles, in the absence, more or less complete, of a 

 differentiation into root, stem, and leaf, and in the great 

 complexity, with few exceptions, of their reproductive pro- 

 cesses. 



Those not acquainted with natural science and more familiar 

 with mathematical methods may consider this a very vague 

 definition. But this difficulty is inherent in the subject. 

 Nature, or rather living nature, abbors hard-and-fast lines. 

 She refuses to run into our moulds, and shuts her eyes to our 

 neat systems of classification. With reference to plants in 

 general, there is scarcely a single statement which can be 

 affirmed of them all without exception. We can say little 

 more of them collectively than that they live and grow. For 

 the fungi prevent us from predicating of all plants that they 

 feed upon inorganic materials, that they contain starch, that 



