Burnside. 109 



they have been subjected, we may well wonder that any 

 remnants at all have been left to bear witness of these by- 

 gone ages. 



In the carboniferous system we find evidences in great 

 abundance of the existence of ferns and of plants allied to 

 them at the time these rocks were being formed ; in fact, 

 there is little doubt that our coal measures are composed 

 entirely of plants of this kind, which reached their maxi- 

 mum in point of development at the time these measures 

 came into being. As we proceed onward in the history of 

 the formation of the crust of the earth, we find that ferns 

 are succeeded by pines and firs, and these, in turn, give place 

 to flowering plants. Botanically, pines and firs are more 

 complex than ferns and mosses, but are surpassed in com- 

 plexity by the flowering plants which show a distinct 

 structural advance on either of the previous groups. 



Here, then, the fossils teach us Nature's work in the long 

 ago, and show us how complete is the gradual advance from 

 the simplest to the most complex forms ; and nowhere is this 

 advance shown so completely as in the development of the 

 flowers or reproductive organs. 



Let us see how the fern is reproduced. On the fronds, in 

 varying positions, and at different seasons of the year de- 

 pending on the species of the plant, are found small brown 

 masses. Here, on the bracken, we see them forming on the 

 under surface of the fronds ; in other ferns we find that 

 they sometimes form rims to the fronds, sometimes lines, at 

 other times rings on their under surfaces. These brown 

 masses are composed of a number of minute cells, each of 

 which is called a spore. When the spores fall to the 

 ground they germinate, but, instead of immediately pro- 



