713 



the sea, the " Old West" river and the "Lark " arc as yet free of it, 

 except just above their confluences. Looking at these facts, I would 

 ask, — If it be a native, how is it that it has never exhibited its extra- 

 ordinary powers of increase till now ? — for, if it be not new, we must 

 suppose that a new property has recently been imparted to it, which- 

 is absurd ; and what better proof of its newness can be offered than by 

 the facts made patent, that it is only now in the act of descending our 

 rivers ? To my mind the evidence is conclusive that it is a foreign 

 importation ; and it is not until we are satisfied on that point that we 

 can properly discuss the question of, Whence came it ? 



Now, this is a point on which no ex cathedra dictum can at pre- 

 sent be pronounced. The question can only be settled by a careful 

 comparison of our plant with its congeners in other countries. It ap- 

 pears, however, that plants of the genus Anacharis are confined to the 

 American Continent, and that one plant, called Anacharis Nuttallii, 

 or Udora Canadensis, very closely resembling, if not identical with, 

 ours, is found in the American rivers. Dr. Johnston has specimens 

 from Dr. Maclagan, gathered in Detroit River, which exactly resem- 

 ble his Berwickshire plant, save only a slight difference in the out- 

 line of the leaves. 



The American plant is frequent in the rivers from Canada to Virgi- 

 nia. I think, therefore, we may safely answer the question of " whence 

 it came," by saying " from North America."* 



But then, How did it get here ? Now, there are various ways va 

 which a plant may be imported. A botanist, in the ardour of that 

 botanical instinct which prompts him to surround himself with as 

 many as possible of the beautiful and varied forms of vegetable life, 

 might have introduced it ; but we have no evidence that such has 

 been the case, although botanists have been known to do such things. 

 If one might hazard a conjecture, I should say that it was most likely 

 introduced, at or about Rugby, with American timber, during the exe- 

 cution of some of the numerous railways which meet at that point. 

 We know that in North America the timber is floated in rafts down 

 the rivers, in which case fragments of the American weed would cling 

 to it, or seeds might find their way into the clefts of the wood ; and if 

 but one seed or one fi'agment retained its vitality, in some moist cranny, 



* I observe a correspondent of the ' Stamford Mercury,' signing himself" Caledo- 

 niensis," affirms that the plant is an importation from Mprway ; but, as it does not 

 appear that it is found in Norway, or, indeed, anywhere on the Continent, I cannot 

 subscribe to his assertion. 



VOL. IV. 4 Y 



