STRUCTURE OF THE PLANT 



little black cones still surviving on their tips (fig. 13). 

 Such a scene always strikes us as strange and uncommon. 

 Involuntarily one feels that this vegetation is totally 

 different from that left behind at the top of the ravine. 

 This subconscious 

 impression is no 

 illusion. This 

 world of ferns and 

 horse-tails is in 

 very truth a singu- 

 lar world ; it is a 

 sample of the vege- 

 table world which 

 used to cover 

 our planet in by- 

 gone geological 

 epochs. Those 

 ferns and horse- 

 tails, and other 

 plants closely re- 

 lated to them and 

 very common in 

 our woods, like 

 these dry, moss- 

 like, creeping 

 plants, with their 

 yellowish cones 

 occasionally up- 

 raised, called club- 

 moss (fig. 14), 

 all these plants, 

 I say, or rather 

 forms related to 



them, used to FIG 



be the prevalent 



vegetation on our planet in the period when our 

 coal-beds were formed. Coal contains the remains of 



