ii4 



species do this, and Woodwavdia ovientalis and others. 

 Other species, such as W. vadicans, several adiantums, 

 and the Walking Fern (Camptosonis vhyzophylliis) bear buds 

 at or near their terminal points, so that the decumbent 

 fronds touching the soil root into it and so spread afar like 

 our common bramble. Ferns, indeed, while steadfastly 

 maintaining these fundamental differences, have adopted 

 most of the contrivances of flowering plants for spreading 

 themselves abroad, despite their persistent restriction as 

 regards the one mode of spore distribution described and 

 common to all genera, although flowers have adopted a 

 thousand and one different methods of getting their seeds 

 distributed. Thus, while many, indeed most, ferns pro- 

 pagate themselves by side shoots or off-sets, some of them 

 like Nephrolepis and Struthiopteris improve upon this by 

 sending out runners under or over the ground, which 

 here and there develop buds and plants far away it may be 

 from the parents, obviously a great advantage. 



A number of species, also, like our Polypodies and 

 Bracken (Pteris aquilina) achieve the same ends by travel- 

 ling rhizomes, i.e. more or less fleshy root stocks which 

 send up single fronds in succession as they progress, and 

 do not, like the species previously cited, form isolated 

 shuttlecock crowns when they develop plants. These 

 travelling rhizomes are often very fleshy, and constitute 

 reserves of nourishment which enables the fern to survive 

 and rise again after periods of drought or heat, which 

 might otherwise prove fatal. Some travel close to or 

 upon the service, and in this way find congenial habitats 

 on tree trunks and similar situations where soil proper is 

 non-existent. Others, like our Bracken, burrow very 

 deeply, and it is interesting to note how a seedling 

 Bracken at its third or fourth frond forms a green bud at 

 the side which, abjuring the light, plunges perpendicularly 

 into the soil to emerge perhaps, like a diver, a foot away 



