12 THE CANADIAN POND-WEED 



later, beds of a weed new to English botanists were 

 found to have taken possession of certain reaches in 

 the Cam, and great was the throwing up of scientific 

 hats at this notable addition to the British flora, which 

 received the name Anacliaris alsinastrum. But in 

 fulness of time the Anacharis of the Cam came to be 

 identified with the Elodea of Canadian lakes, and the 

 murder was out the sprigs thrown out of the pro- 

 fessor's dressing-room had found a congenial home in 

 an English river. Moreover, the newcomer soon spread 

 beyond the hospitable bosom of the Cam. Getting into 

 the canal system, it threatened to bring to a standstill 

 the traffic, which was of vastly greater importance in 

 those days than it is now ; so that an opinion gained 

 ground in commercial circles that either the professor, 

 or his housemaid, or both of them, should be put to 

 a violent and painful death. One circumstance alone 

 seemed to mitigate the disaster. Elodea canadensis 

 is a dioecious herb, bearing, like the aucuba and holly, 

 male and female flowers on different plants. The 

 professor's specimens happened to be all of the mas- 

 culine gender, therefore no seeds could be produced. 

 It is true that this irrepressible weed has the property 

 of breaking itself into innumerable fragments, each one 

 of which inaylgrow into a huge continent of vegetation ; 

 but the lakes and streams of Great Britain are not 

 contrived on a scale to support the prodigious growth 

 which might ensue on a periodic discharge of fertilised 

 seed. Hitherto Elodea has been known in British 

 society only as a bachelor ; let no professor nourish 



