20 



The Naturalist. 



way to the ovules and enter them through a minute hole at their 

 apex, and thus fertilize them. From the union of the pollen tubes 

 with certain cells in the ovule, the young plant takes its rise. The 

 fertilized ovules develop into seeds, each of which contains an embryo 

 or youjig plant ready formed. When the seed germinates, the young 

 plant bursts the seed coats and pushes forth root, stem, and leaves, 

 the seed itself decaying. 



In the so-called flowerless plants, the parts corresponding to the 

 flowers, when present, are minute inconspicuous organs, called anthe- 

 ridia and archegonia, quite unlike stamens and pistils ; hence these 

 plants are called by botanists Cryptogamia— i.e. plants with concealed 

 organs of reproduction. 



The antheridia are club-shaped organs made up of cells, each of 

 which contains a minute filament, which when liberated by the 

 bursting of the cell, swims freely with a wriggling movement ; these 

 filaments, which closely resemble what we meet with in the animal 

 kingdom, are the fertilizing particles. The archegonia are clusters 

 of cells from which, when fertilised, the young plant or the spores are 

 developed. The process of reproduction is, however, so different in 

 different orders of flowerless plants, that no general description can 

 be given ; in very many cases we find two or even more methods of 

 propagation in the same plant, and in a large number of species the 

 true sexual reproduction is very rare, or altogether unknown. In the 

 higher orders of cryptogams the remarkable phenomenon of " alter- 

 nation of generations " is met with analagous to what is found in 

 ^ome animals, as the aphides, described by Mr. Hunter in his paper; 

 the life history of the plant presents two stages — a nutritive non- 

 sexual stage, and a reproductive sexual stage. The germs of the 

 cryptogams are ^' spores," not " seeds," the difference being that the 

 "seed" contains the young plant, the " spore " becomes the young 

 plant. Among the cryptogams we meet with a far greater diversity 

 of form and function than among the higher plants, and many of the 

 lower forms present phenomena of movement, and processes of 

 nutrition, very like those of lowly organised animals. Indeed the 

 two great kingdoms of animals and plants, so widely divergent as 

 regards their higher members, approach each other so closely below, 

 that it is very difficult to draw the line between them, and there are 

 several groups (as the sponges among animals, and the diatoms and 

 volvocineae among plants) which form a sort of debateable ground 

 the possession of which was disputed by botanists and zoologists for 

 years before they were finally ceded to one or the other. A similar 



