The Fern Alliance 



of a Selaginella-like club-moss (Lepidodendron Vel- 

 theimianum), and one can see the splitting of the spore- 

 coat.^ 



That such rare and delicate forms of vegetable life 

 as fungi, spore-tubes, and the prothallia, which grew in 

 Palaeozoic times, have come down to us is sufBciently 

 marvellous, yet gives a very deceptive impression of our 

 knowledge of the Carboniferous period. 



It is not certain whether the atmosphere was cold or 

 a damp, steamy heat. Professor Henslow has tried to 

 show that the climate was dry and not damp, but this 

 theory has not been accepted by most geologists and 

 botanists.^ Mosses do not seem to have been nearly as 

 abundant as one would have thought likely, but the peat- 

 mud-like character of what is now coal is like the peaty 

 humus of the forests of Valdivia or Punta Arenas in Chile, 

 of the summit of Ruwenzori, or even of the oak and birch 

 clumps at the edge of a peat-moss in Scotland. 



It was, in the author's opinion, a damp, still, and 

 steamy atmosphere certainly, but not necessarily a very 

 hot or even a subtropical climate. 



But the real difficulties and dangers of this chapter 

 begin when one tries to give even a sketchy impression 

 of the great and important discoveries which have been 

 made by many English botanists, who have laboriously 

 examined the actual plants which lived in the forests. 



So far we have been, intentionally, as vague as possible 

 about them. 



Von Wettstein, in a recent publication,^ sketches in 

 a very interesting way the general course of develop- 

 ment of the great groups of plants. 



The algse were water-plants. The mosses begin life 

 as a green thread-like mass called the protonema, which 

 is exactly like an alga and also lives in water. Yet 

 their stems are in most cases formed in air. 



83 



