232 THE TWO FLORAS, 



they assume at their line of meeting directly antagonistic 

 hues. 



But what does experience say regarding the transmutative 

 conversion of a marine into a terrestrial vegetation, — that ex- 

 perience on which the sceptic founds so much. As I walked 

 along the green edge of the Lake of Stennis, selvedged by 

 the line of detached weeds with which a recent gale had 

 strewed its shores, and marked that for the first few miles 

 the accumulation consisted of marine algae, here and there 

 mixed with tufts of stunted reeds or rushes, and that as I 

 receded from the sea it was the algae that became stunted and 

 dwarfish, and that the reeds, aquatic grasses, and rushes, grown 

 greatly more bulky in the mass, were also more fully deve- 

 loped individually, till at length the marine vegetation alto- 

 gether disappeared, and the vegetable debris of the shore be- 

 came purely lacustrine, — I asked myself whether here, if any- 

 where, a transition flora between lake and sea ought not to 

 be found 1 For many thousand years ere the tall gray obe- 

 lisks of Stennis, whose forms I saw this morning reflected in 

 the water, had been torn from the quarry, or laid down in 

 mystic circle on their flat promontories, had this lake ad- 

 mitted the waters of the sea, and been salt in its lower reaches 

 and fresh in its higher. And during this protracted period 

 had its quiet, well-sheltered bottom been exposed to no dis- 

 turbing influences through which the delicate process of trans- 

 mutation could have been marred or arrested. Here, then, 

 if in any circumstances, ought we to have had, in the broad, 

 permanently brackish reaches, at least indications of a vege- 

 tation intermediate in its nature between the monocotyledons 

 of the lake and the algae of the sea j and yet not a vestige 

 of such an intermediate vegetation could I find among the 

 up-piled debris of the mixed floras, marine and lacustrine. 

 The lake possesses no such intermediate vegetation. As the 

 water freshens in its middle reaches, the algse become dwarfish 



