9° 



HA RB WICKE'S SCIENCE- G OSSIF. 



p. 270). A few additional notes might be of interest. 

 I sent to my brother, who is employed at the above 

 factory, a note asking him to get a few alive for me, 

 and made arrangements with him to get them here, 

 which he did on November 21st, 1890, when he sent 

 sixty-two live P. acuta, which I kept alive in tap- 

 water for a period ranging from six to twenty-one 

 days. Strange to say, all the largest specimens died 

 first. The ponds they are found in are filled with 

 hot water summer and winter, so I think the sudden 

 change from hot to cold was the cause of death. 

 Linimza pcregra is very plentiful in the same ponds, 

 but succumbed the same as P. acuta. There is a 

 distinct variety in the P. acuta that is white, and 

 much larger, and the outer lip seems to approach the 

 variety of L. pcregra, var. labiosa, but pure white — a 

 very pretty form, but not so common as type. The 

 above specimens when put in the tap-water were 

 quite lively, and night after night I sat and watched 

 their movements, which were very interesting. Mr. 

 Smith gave me the following information. He is 

 foreman at the Banner Mill, and since he came there, 

 that is, thirteen to fourteen years ago, they have 

 always had a place in the ponds, for the first time 

 he cleaned out one of the ponds he found them there, 

 but how they got there he could not tell me, but for 

 fourteen years they have lived and died in these 

 ponds, and never been heard of till now. This is 

 the first time P. acuta has been found in Scotland ; 

 that is to say, five hundred miles farther north than 

 any other locality, the other locality being London, 

 and, though not a British species, it is interesting to 

 hear of a Continental species getting so far north. 

 Large or small specimens of P. acuta are very 

 difficult to get during the months of September, 

 October, November, and December. Plenty of 

 small ones can be got, but I think the larger speci- 

 mens burrow in the mud at the bottom of ponds. — 

 W. D. Rac. 



Dwarf var. of Helix Sylvatica. — At a place 

 about one thousand feet above Montreux, and some 

 little distance above a bridge known as the Pont de 

 Pierre, I have found a rather remarkable dwarf var. of 

 Helix Sylvatica, Drap. The species is pretty widely 

 distributed in the Alps, but is usually of a larger size 

 than in the above-named locality. It belongs to the 

 same section, Tacliea, Leach, of genus Helix as //. 

 iietnoralis, Linn., and hortensis, Miill. — C. P. Gloync. 



The Flight of Birds.— In reference to the soar- 

 ing flight of birds, under notice in some papers lately, 

 I beg to offer my explanation of flotation in the air by 

 the ability of the bird to reduce or increase its specific 

 gravity by voluntary action. It may be surmised, it 

 is possible that the double larynx may be the means 

 whereby this is effected, where the trachea and two 

 larynges may correspond to the cylinder and two 

 valves of an air pump in pneumatic experiments, and 

 the glass globe or dome .would correspond to the 



lungs and air cavities in the body of the bird. The 

 modus operandi may take effect by contraction of the- 

 length of the intervening trachea down towards the 

 lower larynx, then closure of the upper larynx, 

 followed by elongation of tube upwards towards the 

 head. The intervening column of air inside it would; 

 then be lengthened and attenuated, and the lower 

 larynx would then be closed, so as to preserve the 

 attenuation in the lungs and cavities from the external 

 air. The upper larynx would then be opened and the 

 air let in, and the contraction of the trachea would 

 again take place, and the action of attenuation of air 

 as before repeated up and down. If these efforts- 

 were renewed so many times in a second, with 

 intervals for ordinary respiration, then an ascent to 

 one thousand feet would take place as rapidly as in 

 any balloon. In order to establish this procedure on 

 a scientific basis it would be requisite to take the 

 weight of a certain bird at the level of the earth, and 

 at a height of one thousand feet ; or instead to ex- 

 haust the air out of the lungs to the extent of one 

 inch of the barometer, and weigh it again, and also 

 to ascertain the weight of the air in the body of the 

 bird and its volume, at the level of the earth, and at 

 a height of one thousand feet, or a reduction of one 

 inch of mercury. The rapid descent of the bird would 

 be effected by reversing the above process of air pump 

 exhaustion, and converting the trachea and its double 

 larynges into a force pump, so as to fill the lungs and 

 cavities with air of a greater density. The buoyancy 

 of the bird might then be made out for flotation in its 

 medium, in a like manner as is done for torpedoes, 

 diving-bells, balloons, &c., and the modus operandi 

 of towering rendered more clear of comprehension. — 

 " O/'server." 



BOTANY. 



The Flora of Kent. — Seeing your questions on 

 the Flora of Kent in this month's Science-Gossip, 

 I thought I would write and tell you that, having, 

 read and come across any amount of books in science, 

 natural history, &c., I do not remember ever having 

 seen a Flora of Kent. The nearest I know of is the 

 "Flora of Middlesex, with Map of Botanical Dis- 

 trict," by II. Trimen, 12s. 6d., published by \V. H. 

 Allen, 13, Waterloo Place, Pall Mall, London, S.W. 

 If you have a copy of G. P. Bevan's "Kent," 2s. 

 (Stanford's "Tourist Guide Series," published by 

 Stanford & Co., 55, Charing Cross, London, S.W.), 

 you will most , probably find, either at the very 

 beginning or very end of the book, the topography, 

 history, biography, archeology, geology, mineralogy, 

 fauna and flora, botany, mining, manufactures, and 

 agriculture of the county. At the end of the intro- 

 duction the author gives a list of the best books on 

 the county, including botany, geologj', &c. You 

 may hear of a Kentish Flora in this way. N.B. — 



