respectively by the Ferns and their allies, Club-mosses and 

 their allies, and the isolated Horsetails, now reduced to 

 a single genus. In this group first occurred forms of 

 terrestrial vegetation, which would now be called trees. We 

 must lay stress upon the word terrestrial, for no one can 

 now tell what glorious and luxuriant algal forests may have 

 grown in primeval seas, without leaving a trace behind them, 

 except amorphous masses of graphite. The Pteridophytes 

 are also known as the Vascular Cryptogams, in opposition to 

 the two preceding groups, which may be called Cellular 

 Cryptogams. They possess true roots and fibro- vascular 

 bundles, and the capacity of taking on a woody structure. 

 Dissimilar as the outward habit of a fern, a horsetail, and a 

 club-moss may appear at first sight, they are all connected 

 together by the character of their prothallus. This is a kind 

 of nurse plant or preliminary stage, in which a cellular ex- 

 pansion arises from the germinating spore, and in time pro- 

 duces the anther idia and archegonia. From the fertilised 

 archegonium springs the form which we call, in ordinaiy lan- 

 guage, the fern or the horsetail, and this form, in its turn, 

 gives rise exclusively to asexual spores. In the small group 

 of Heterospores the extension and duration of the prothallus 

 are so abbreviated that the two kinds of spores, the micro- 

 spores and macrospores, approach in function very near to 

 pollen-grains and ovules. But to the last antherozoids occur, 

 and require water : a mark distinguishing the highest Hetero- 

 spore from Phanerogams. 



Advancing now to Flowering plants, we have the advantage 

 of being able to appeal to common knowledge. Everybody 

 has some notion of a flower and its parts. The sub-kingdom 

 of Phanerogams is divided into two classes, of equal systematic 

 importance, but very unequal in extent. Here, as in earlier 

 instance's, we must distinctly bear in mind that the vegetation 

 of the present epoch is only a temporary phase of the develop- 

 ment of plant-life. Paleeontology teaches us that classes now 

 small in extent were once more important, and it is only by 

 taking a broad view of past as well as of present life that we 

 understand the relative value of the higher groups. In natural 

 as well as in political history the present has its roots in the 

 past, and is now determining the future. It is thus with the 

 two classes of Phanerogams, Gymnosperms and Angiosperms. 

 If we considered only the actual state of affairs, the Gymno- 

 sperms would appear to be what they were considered in pre- 

 geological times, a subordinate group. But when we know 

 that they date as far back as the Devonian beds, we see their 

 importance in the great plan of creation. The Gymosperms 



