15 
the execution 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 dut one seed, or 
one fragment retained its vitality, in some moist cranny, till it 
reached its final destination, I verily believe it would be 
sufficient to account for the myriads of individuals that now 
exist in England. Indeed, from the circumstance of all the 
plants hitherto found being of one sex, the hypothesis of its 
propagation from a single seed or fragment is rendered more 
probable than by supposing a number of seeds or fragments 
to have been imported. 
But some one will be asking, as the plant could not have 
found its way by water from Rugby or Watford to Cam- 
bridge, how came it in the Cam? This question through the 
kindness of Mr. Basineton, I am enabled to answer dis- 
tinctly. In 1847, a specimen from the Foxton Locks was 
planted in a tub in the Cambridge Botanical Garden, and in 
1848, the late Mr. Murray, the curator, placed a piece of 
it in the Conduit stream, that passes by the new garden. In 
the following year, on Mr. Banineton asking what had 
become of the stick which marked the site of the plant, he 
was informed that it had spread all over the ditch. From 
this point it doubtless escaped by the waste pipe across the 
Trumpington Road, into the ¢ Vicar’s Brook,” and from 
thence into the river, above the Mills, where it is now found 
in the greatest profusion. In the case of the Cam, then, we 
see it proved to demonstration that the short space of four 
years has been sufficient for one small piece of the * Anacharis” 
to multiply so as to impede both navigation and drainage. 
When Proressor Gray, of Boston, U.S., was at Cam- 
bridge, Mr. BABINGTON mentioned the circumstances to him, 
at which he expressed surprise, as the Anacharis is not found 
