HARDWICKE'S SCIENCE-GOSSIP. 



227 



is one of our most distinguished workers. Dr. Sorby's 

 address, in the geological section, turned chiefly upon 

 the microscopical examination of sections of slag and 

 other artificial fused rocks, and a comparison of them 

 with such natural igneous rocks as granite and 

 basalt, &c. Excursions were made to the chief of 

 the localities described by Mr. H. B. Woodward, in 

 his papers contributed to Science-Gossip on the 

 "Geology of Swansea and the Neighbourhood." 



One noticeable feature in connection with this 

 year's meeting was a conference of delegates from 

 various scientific societies, who met under the presi- 

 dency of Mr. John Hopkinson, F.L.S., Hon. Sec. of 

 the Hertfordshire Natural History Society, to discuss 

 the possibility of a closer union between provincial 

 scientific societies. Mr. Hopkinson further remarked 

 that the list of delegates prefixed to the list of 

 members usually attending the annual meeting of the 

 Association was practically useless. Mr. Hopkinson 

 had, therefore, proposed that the secretary of any 

 scientific society publishing Transactions, as well as 

 the president, should be temporary members of the 

 General Committee. 



At the meeting of the Council of the Association, 

 on Monday, August 29, it was resolved to hold the 

 next meeting at York. Sir John Lubbock was elected 

 president, and the following distinguished scientific 

 men, all of whom, except the Archbishop of York, 

 have passed the presidential chair, were elected vice- 

 presidents : His Grace the Archbishop of York ; 

 Mathematics and Physics, Sir William Thomson ; 

 Chemistry, Professor Williamson ; Geology, Professor 

 Ramsay ; Biology, Professor Owen ; Geography, Sir 

 J. D. Hooker ; Mechanics, Sir William Armstrong. 



NOTES ON THE WATER THYME {ANA- 

 CHARIS ALSIXASTRUM, Bab.) 



FIRST OCCURRENCE OF ITS MALE FLOWERS 

 IN BRITAIN. 



11 7HATEVER may be the fate of the Colorado 

 V V Beetle when it arrives on our shores, there 

 can exist no doubt that the American colonist, 

 whose botanical name is given above, has found a 

 congenial home in Britain. When or how the New 

 Waterweed (as it is sometimes also called) was 

 introduced into this country, appears to be uncertain. 

 Professor Oliver says it was first remarked in Britain 

 in 1S17, and Sir. J. D. Hooker says it was in- 

 troduced into county Down about 1836, and into 

 England about 1841. In 1847 it was observed by 

 Miss Kirby in Leicestershire, and was first described 

 as a British plant by the late Dr. G. Johnstone of 

 Berwick-upon-Tweed, in his " Botany of the Eastern 

 Borders," published in 1853. At page 191 he gives 

 the following account of the plant : " I found this 

 plant on the 3rd of August 1842 at Dunse Castle in 



profusion. I noticed it nowhere else until 9th 

 August, 1S48, when I found a few tufts of it at 

 Newmills, in the Liberties of Berwick, and in 

 September of the same year I discovered it in 

 abundance at a deep and still reach of the White- 

 adder, between Whitehall and Edington Mill. In 

 the summer of the following year the plant was 

 noticed in many intermediate localities, and in 1850 

 it had occupied almost every part of the river where 

 the water ran sluggishly, almost to choking. This 

 was so much the case at Gainslaw Bridge that the 

 weed was dredged out with grapes. It multiplied 

 and became a noxious weed in 185 1 and 1852 and 

 now had spread itself below the bridge unto within 

 half a mile of the river's confluence with the Tweed. 

 No means seem to arrest its diffusion, and it will be 

 found that the principal opponent of its evil pro- 

 pensity to multiply is a spate — a heavy spate, of a 

 few days' continuance. This carries away large 

 quantities. After one of them the plant is found 

 strewed along the sides of the Tweed, and at the end 

 of September, 1852, I saw many cartloads of it 

 thrown upon the shore at Spittal." 



When the above was written the anacharis had 

 not made its appearance in the Tweed, but Mr. 

 Brotherston informs me that it is now abundant in 

 the lower part of that river, which it is said to be 

 ascending at the rate of a mile every year. It is 

 a great pest to the salmon-fishers, as large masses of 

 the plant are constantly getting entangled in their 

 nets. It is very brittle, and the smallest piece, if it 

 has a whorl of leaves, is capable of sending down 

 roots to the soft mud wherever it happens to rest ; 

 and as it sends out horizonal shoots that rise and 

 spread every five or six inches along the bottom of 

 lakes and streams, it multiplies with extraordinary 

 rapidity, which is rather increased than diminished 

 by the ordinary method of trying to destroy the plant 

 by breaking up its masses. It is now very abundant 

 and troublesome in many lakes and canals throughout 

 Britain*; is found in most of the ponds and lochs in 

 this neighbourhood, and the end of the Union Canal 

 at Edinburgh is almost choked with it. It is 

 greedily eaten by swans and other waterfowl, and as 

 "horses are very fond of it, and will wade into deep 

 water to feed upon it," it might be used as a useful 

 addition to hay for a forage plant. 



I need hardly say that the anacharis is well known 

 to young microscopists from the fact that its tangled 

 masses are the favourite haunts of hundreds of 

 Entomostraca, Rotatoria, Infusoria, and other minute 

 forms of animal life ; and for the ease with which the 

 beautiful intra-cellular motion known as rotation or 

 cyclosis is seen in its leaves. For this purpose all 

 that is necessary is to cut off a leaf, place it in a drop 

 of water on a slide, put it under the microscope, and 

 view it by the aid of transmitted light. The little 

 granules of chlorophyll will now be seen constantly 

 moving round within the walls of the large and 



