FERNS 141 



society of large and shady trees, cool streams with overhanging 

 banks, the mouths of rocky caverns, and deep-cut lanes, often 

 haunted by the rarer birds and mammals. Some ferns, however, 

 prefer an open place to live in, such as the bracken, which sometimes 

 covers many square miles of country ; but this is exceptional, and 

 the student will not have to think very long before the explanation 

 of why most ferns love shade will occur. 



Then, again, hunting for prothalli, the little heart-shaped plants 

 to which the fern spores give rise, and which will bear the eggs of 

 the new generation, is no easy matter. The plant is usually but a 

 fraction of an inch in length, and requires some looking for. We 

 have found prothalli in the decaying wood of old tree stumps, 

 and well remember the triumph when a prothallus, hitherto only 

 known to us from books, was discovered for the first time. The 

 growth of young fern leaves is always interesting to watch, as they 

 unroll in the spring from the dead-looking clump, and one notes 

 the long red hairs which drop off later. What is their function ? 

 At present we do not know. If ferns are insignificant nowadays, 

 they were of the greatest importance in earlier ages. It is difficult 

 to realise that the vast amount of energy given out in the form of 

 heat by burning coal by which, when used in steam engines, such an 

 enormous amount of work is done, is really the energy of the sun- 

 light which caused the ferns to grow countless ages ago, yet such is 

 really the case. It brings irresistibly to the mind the story in the 

 " Arabian Nights " of the genie who was for thousands of years bottled 

 up in the vase which the fisherman drew to the shore in his net, and 

 when set free grew to huge proportions ; a fairy tale which is 

 exactly paralleled by the story of the coal forests. We will conclude 

 by quoting from Mr Scott Elliott's description of a Coal Measure 

 landscape : " The atmosphere was saturated with moisture, and the 



