12 BULLETIN OF THE NATURAL HISTORY SOCIETY. 



Upon the under side of the prothalHa of Ferns seems to be 

 a distinct adaptation for placing them where the water 

 necessary for their fertihzation is most abundant. Yet 

 experiments show that they seek not the wettest but 

 the darkest side, and if Hght be thrown up upon them 

 trom below, these organs develop upon the upper surface. 

 Indeed, ver}' few facts can be settled from observation 

 alone ; it is always better to confirm observation by 

 experiment. Again, one must be on the watch lest he 

 take single individual adaptations or accidents or sports, 

 as characteristic of the whole species. The power of 

 individual response to certain special conditions is in some 

 plants remarkably great, and it may accidentally or in- 

 tentionally be brought about. The result may be 

 extremel}' valuable for some purposes, but it is not a safe 

 guide to the real cause of adaptation in a state of nature. 

 Numerous observations under varying conditions in the 

 field, with concise control-experiments — these, we repeat, 

 are the tools of the local phytobiologist. 



It remains in this connection but to point out that there 

 are three phases of phytobiological study to be applied 

 to ever}' plant. There is first the investigation of the 

 raison cVetre of the characteristics of its individual parts ; 

 secondly, the eousideration of it as a member of a bio- 

 logical group ; and thirdly, its consideration as a member 

 of a climatic group. The Sundew catches insects in one 

 way, Nepenthes in another, thus showing individual 

 adaptations ; both have characteristics in common as 

 members of the biological group Insectivora, while the 

 former has yet other characteristics in common with its 

 neighbors in cold northern bogs, the latter with other 

 epiphytes in damp tropic forests. Salicornia and a Cactus 

 have habits different enough, yet they have many charac- 

 ters in common as members of the biological group of 



