MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMIA. 351 



seem to have borne 'megaspores' in the sporangia of its basal portion, 

 and ' microspores ' in those of its upper part. Some of the best seams, 

 of Coal appear to have been chiefly formed by the accumulation of these 

 ' megaspores. ' 



348. Thus, in our ascent from the lower to the higher Cryptogams, 

 we have seen a gradual change in the general plan of structure, bringing 

 their superior types into a close approximation to the Flowering Plant, 

 which is undoubtedly the highest form of vegetation. But we have 

 everywhere encountered a mode of Generation, which, whilst essentially the 

 same throughout the series, is no less essentially distinct from that of the 

 Phanerogam; the fertilizing material of the 'sperm-cells 7 being embodied, 

 as it were, in self-moving filaments, which find their way to ' germ-cells * 

 by their own independent movements; and the ' embryo-cell ' being des- 

 titute of that store ef prepared nutriment, Avhich surrounds it in the true 

 Seed, and supplies the material for its early development. In the lower 

 Cryptogamia, we have seen that the fertilized oospore is thrown at once 

 upon the world (so to speak) to get its own living; but in Ferns and 

 their allies, the ' embryo-cell ' is nurtured for a while by the prothallium 

 of the parent plant. While the true reproduction of the species is effected 

 by the proper Generative act, the multiplication of the individual is ac- 

 complished by the production and dispersion of ' gonidial ' spores; and this 

 production, as we have seen, takes place at very different periods of exist- 

 ence in the several groups, dividing the life of each into two separate epochs, 

 in which it presents itself under two very distinct phases that contrast, 

 remarkably with each other. Thus, the frond of the Marchantia evolved 

 from the spore, and bearing the antheridia and archegonia, is that which 

 seems naturally to constitute the Plant; but that which represents this; 

 phase in the Ferns is the minute Marchantia-like prothallium. In Ferns, 

 on the other hand, the product into which the fertilized 'embryo-cell' 

 evolves itself, is that which is commonly regarded as the Plant: and this 

 is represented in the Liverworts and Mosses by the spore-capsule alone. 1 

 We shall encounter a similar diversity (which has received the inappro- 

 priate designation of ' alternation of generations ') in some of the lower 

 forms of the Animal Kingdom. 



1 For more detailed information on the Structure and Classification of the Cryp- 

 togamia generally, the reader is referred to Prof. Sachs' " Text-book of Botany," 

 (Bennett's translation), and to Prof. Hofmeister's large " Handbuch der Physi- 

 ologischen Botanik." 



