I 



have been addling my brain and straining my eyes över a set of ignoble Pond- 

 weeds (alias Potamogeton) trying to find the difference there should be 'Twixt 

 tweedledum and tweedledee, for all of which I suppose nobody will thank me, and 

 I shall get no fee. Indeed, few would see the least sense in devoting so much time 

 to a set of vile little weeds. But I could not slight them. The Creator seems to 

 have bestowed as much pains on them, if we use such a word, as upon more conspi- 

 cuous things, so I do not see why I should not try to study them out. » 



Asa Gray. 



