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of life until the latter half of last century without leaving 

 any traces of suprasoriferation, although it must have 



been a possibility all along, and does not appear to be much 

 of a handicap in the struggle for existence. We now sec 

 occasional traces of suprasoriferation in almost every fertile 

 variety of Scolopendrium. These traces could be accentu- 

 ated and perpetuated indefinitely by a process of selection, 

 if such a thing were desirable. 



I know nothing more fascinating than to watch the 

 gradual ripening of the spores in a bed of suprasoriferous 

 Scols. The spores being in great measure on the upper 

 surface, are nearly all visible from above, and the gradual 

 changes in colour, from white to black, and lastly to brown, 

 are a perpetual feast. 



As to the reason for this gradual migration of the sori from 

 the under to the upper surface, there is nothing definitely 

 known, and we can only surmise. 



The most reasonable hypothesis as to why spores should 

 usually be produced on the undersides of the fronds is : 

 that since the upper surface is always harder and more 

 leathery than the under, it would require a lesser effort to 

 develop the sori through the softer and more yielding under 

 surface, than through the glazed, tougher and more leathery 

 upper surface. On the under surface also the spores would 

 be kept drier and in better condition for germination, and 

 would also be more quickly and effectually evacuated and 

 distributed. Any advantage, however slight, possessed by 

 any plant would tend to be reproduced in succeeding 

 generations, and would tell in the long run, in the stru 

 for existence. 



In the narrow marginate forms, the tissues all the length 

 of the frond are contracted int., a sort of ridge or tidal wave, 

 to produce the marginate character. In order i<» form this 



