6 
PROCEEDINGS OF SOCIETIES. 
these parts are called regular, when not so, they are irregular ; some forms of the 
latter are peculiar to certain natural families, and we observe fixed conditions of 
form and colour. The colours of plants are regulated by generally understood 
principles—viz., that a certain primary colour is associated with a certain secondary, 
which is its complement—that is to say, the two together contain all the elements 
of wdiite or compound light. Relations of structure of position, and of number, 
have long been familiar to botanists; such betweeen colour'and form are not less 
obvious and interesting. In regular corollse there is not only uniformity in the 
size and shape of the different pieces, but also in the distribution of the colour or 
colours, when, as is often the case, two are present, and these two a primary and its 
complement. When the corolla is irregular, so also is the distribution of the colours ; 
and in flowers whose parts are arranged on the quinary type, the piece, called by 
botanists the odd lobe, may be usually distinguished by its colour, which differs 
from that of the others. 
CORK CUVIERIAN SOCIETY. 
DECEMBER 6, 1854. 
Professor Boole, LL.D., in the Chair. 
Professor Murphy read the following paper 
ON THE ANACHARIS ALSINASTRUM, 
And produced some specimens taken from the Bishop's brook. The plant is a 
native of Canada and other parts of North America, in which five or six species are 
found. This weed has attracted a good deal of public attention in England during 
the past few years, from its tendency to choke up drains and obstruct the navigation 
of canals and rivers. The species (alsinastrum) is said to have been first observed 
in Britain, in 1842, by Dr. George Johnston, of Berwick, who found it growing 
in the lake at Dunse Castle, in Berwickshire. It was also discovered in the Junc¬ 
tion Canal, at Market Harborough, in Leicestershire. Attention was drawn to it 
by Mr. Babington, in a paper read before the Botanical Society of Edinburgh, in 
December, 1847. It was next observed by Mr. Marshall, of Cambridgeshire, in 
August, 1852, at which time it was also noticed by many persons in different parts 
of England. He thinks it was introduced by a seed, or a portion of the living plant 
attached to timber floating down some of the rivers of Canada. Mr. Babington 
thinks it may have been introduced with aquatic plants from America. The 
Anacharis, when once introduced, would, in a few years, spread into any connected 
water system from one end to the other, and is thus supposed to have been dissemi¬ 
nated through the midland districts of England. A bit of it was planted in Cam¬ 
bridge Botanical Gardens, whence it got into the Cam, and it needs no longer be 
sought for; it may be found everywhere, in more or less quantity, from Cam¬ 
bridgeshire downwards, choking up the mouths of docks, sluices, and narrow 
watercourses, and in the upper portions of the river, impeding both navigation and 
drainage. If it should continue in anything like the same ratio as it has done, the 
upper parts of the river will no longer be able to pass their waters to the sea, and 
the navigation interest may surrender to the railways what little remains to them 
of the carrying trade. That it is already a source of annoyance to our watermen 
is evident by the universal complaints which have been made of the obstructed state 
of the River Cam. Sluice-keepers complain that masses of it get into the pen, and 
when the slackers are drawn, the openings are choked, and the operation of letting 
boats through is greatly impeded. The railway dock at Ely became so choked with 
the weed that the boats could not enter until several tons of it had been lifted out. 
Rowers, too, found it interfere with their amusements; and swimmers remarked 
