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HARDWICKE'S SCIENCE-GOSSIP. 



disease similar to that of vaccination in relation to 

 smallpox. By cultivation a modified growth of the 

 anthrax parasite is obtained, which is then used in 

 order to inoculate cattle and sheep with a mild form 

 of the disease, such inoculation having the result of 

 rendering the cattle and sheep free from the attacks 

 of the severe form of disease, just as vaccination or 

 inoculation with cowpox protects man from the 

 attack of the deadly smallpox. One other case I 

 may call to mind, in which knowledge of the presence 

 of bacteria as the cause of disease has led to suc- 

 cessful curative treatment. A not uncommon afflic- 

 tion is inflammation of the bladder, accompanied by 

 ammoniacal decomposition of the urine. Micro- 

 scopical investigation has shown that this ammoniacal 

 decomposition is entirely due to the activity of a 

 bacterium. Fortunately this bacterium is at once 

 killed by weak solutions of quinine, which can be 

 injected into the bladder without causing any injury 

 or irritation. This example appears to have great 

 importance, because it is the fact that many kinds of 

 bacteria are not killed by solutions of quinine, but 

 require other and much more irritant poisons to 

 destroy their life, which could not be injected into 

 the bladder without causing disastrous effects. Since 

 some bacteria are killed by one poison and some by 

 another, it becomes a matter of the keenest interest 

 to find out all such poisons, and possibly among 

 them may be some which can be applied so as to kill 

 the bacteria which produce phthisis, erysipelas, 

 glanders, anthrax, and other scourges of humanity, 

 while not acting injuriously upon the body of the 

 victim in which these infinitesimal parasites are doing 

 their deadly work. In such ways as this, biology has 

 turned the toy " magnifying-glass " of the last century 

 into a saver of life and health. 



Association of Helix nemoralis and H. 



HORTENSIS, AND OTHER CONCHOLOGICAL NOTES. — 



Anyone referring to an article which I contributed 

 to the January number of Science-Gossip, will find a 

 record there of the finding of Helix nemoralis and 

 H. hortensis on one plant stem. Since then I have 

 been most fortunate in finding a hedgebank, whereon 

 //. nemoralis and //. hortensis are intimately 

 associated. Also at Miller's Dale and Monsal Dale, 

 in Derbyshire, I have found the two together. I 

 trust to contribute an article dealing with their 

 variation, and making some observations thereon. I 

 am sure that conchological students, many of whom 

 wrote me so kindly after the appearance of 

 the above article, will hear with pleasure of these 

 British finds, which will give us a chance of carrying 

 the subject a step further. Every student of Darwin 

 knows the historical experiment of the duck's feet 

 suspended in an aquarium, until the young molluscs, 

 which were hatched therein, crawled upon them ; and 

 how even an Ancylus may be carried by a water- 

 beetle. Lately, whilst experimenting upon Spharium 



corneum, a bivalve which is extremely common in the 

 canal at Leeds, I observed one specimen being 

 transported about a small aquarium in which I had 

 some of these molluscs, along with five species of 

 gastropods, in a manner which I think worth 

 recording. I had often noticed their aptitude in 

 reaching any part of the weed [Elodea Canadensis) 

 in the vessel, and suspending themselves therefrom, 

 and that they could travel up the glass with the same 

 ease as a gastropod ; a fact not recorded, I believe, in 

 this species. But when I found one using the shell 

 of a very energetic Limncea stagnalis, the observations 

 noted above in the "Origin of Species" came at 

 once to my mind. The sphcerium was attached by a 

 muscular thread ; made up, as could easily be seen, in 

 some positions through a strong lens of several 

 fibres, which was emitted from the middle third of 

 the foot. In this manner it made a tour a whole 

 Saturday afternoon, and beyond withdrawing its 

 siphons, its journey did not seem to incommode 

 it much. The specimen was about half-grown, and 

 so far I have noticed the proclivity in full-grown 

 animals. In the same aquarium I placed, on July 

 16th, three specimens of L. stagnalis, whose shells 

 had been broken in a jagged manner about the 

 mouths, during a railway journey from Stockport 

 here. During a period of little over three weeks, the 

 youngest specimen — a last year shell — has added |th 

 of an inch of new material, and has formed anew the 

 mouth of its shell. The other two specimens, which 

 are more fully grown, have both repaired their shell 

 mouths, but the greatest breadth of new material 

 does not exceed ifh of an inch. — Henry Crowthcr, 

 Beeston Hill, Leeds. 



" Limax flavus." — In the first paragraph of page 

 224 of the present volume is not this a misprint for 

 Limax agrestis ? Various statements both in that and • 

 subsequent paragraphs, as well as the figures them- 

 selves suggest the possibility of this being the case. 

 — W. D. R. 



Migration of British Birds. — The committee 

 appointed to jeport on this subject by the British 

 Association, especially with reference to information 

 derived from lighthouse-keepers, &c, concludes by 

 speaking of the marvellous persistency with which, 

 year by year, birds follow the same lines, or great 

 highways of migration, when approaching or leaving 

 our shores. The constancy of these periodical 

 phenomena is suggestive of some settled law or 

 principle governing the movement. It is clearly 

 evident, from the facts already at our disposal, that 

 there are two distinct migrations going forward at 

 the same time, one the ordinary flow in the spring 

 and ebb in the autumn across the whole of Europe. 

 A great migratory wave moves to and from the 

 nesting-quarters of the birds, in the coldest part of 

 their range, north-east in the spring, and south-west 

 in the autumn. Quite independent of this there is a 



