1. THE ORIGIN OF THE SEED-PLANTS 1) (SPERMOPHYTA) 
Dye IH SCOT TERMES) 
The name Seed-plants or Spermophyta is used to cover the Phanero- 
gams in the widest sense, including Gymnosperms (e.g. Conifers and. 
Cycads) as well as the true Flowering Plants or Angiosperms. Not all 
Phanerogams bear flowers, but all produce seeds. 
In contradistinction to the Seed-plants we have the Spore-plants or 
Cryptogams (e.g. Ferns, Mosses, Seaweeds and Fungi). In all these 
groups the reproductive bodies are minute and simple, usually consis- 
ting of a single cell, while the Spermophyta are reproduced (apart from 
vegetative propagation) by complex bodies, often of considerable size, 
composed of various tissues, and usually containing an embryo. That 
there is a certain relation between these two great divisions of the vege- 
table kingdom has been recognised since the time of Hofmeister (the 
middle of the nineteenth century). 
Taking one of the simpler representatives of the higher Spore-plants, 
such as a Fern, we find that all the spores are of one kind; on germina- 
tion each spore gives rise to an independent plantlet, the prothallus, on 
which the sexual organs are borne. Fertilisation is effected by the 
active male cells or spermatozoids, swimming in water, and the egg at 
once develops into an embryo and forms a new Fern. 
In the more advanced Vascular Spore-plants, such as the Water- 
ferns or Selaginella, the sexual differentiation begins earlier, and the 
spores are of two kinds, microspores and megaspores. The former have 
little more to do than to produce the spermatozoids; the large spores, 
on the other hand, give rise to a fairly massive prothallus, bearing the 
female organs, and serving as a store-house of food for the developing 
embryo. This is to some extent an approach to the conditions in the 
1) Reprinted, with the consent of the author and of the authorities of the Uni- 
versity College of Wales, from the Aberystwyth Studies. Vol IV. p. 219—228. 
