34 



SCIENCE-GOSSIP. 



On page vi. of advertisements in the last number, 

 the address of Mr. Charles Collins, optician, was 

 incorrectly given. It should have been 157, Great 

 Portland Street, London, W., where he has traded 

 for many years. 



We have to hand the Sixth Report of the 

 Microscopical Society of Calcutta, for 1893. The 

 society possesses seventy-eight members, having 

 last year lost three by death, viz., Dr. H. W. Hill, 

 General G. B. Mainwaring and Prof. Wood-Mason, 

 its president. 



Exeter Canal. — It may interest readers of 

 Science-Gossip in this neighbourhood, who are 

 microscopists, to know that they will find the 

 canal a good hunting-ground. I have found among 

 Rotifers, beside a number of free-swimmers, the 

 following tube-dwellers : — Melicerta ringens, M. 

 tubiadaria, Limnia ceratophylli, L. cephalosiphon, 

 GEcistes stygis, Megaceros, Floscularia ornata, F. cor- 

 nuta, F. ambigua, Stephanoceros eichhorni. Of the 

 latter I have several beautiful specimens under 

 observation at the present time (February 30). Of 

 Polyzoa I have found the following : — Fredericella 

 sultana, Lophopus crystallinus, Cristatella mucedo, Palu- 

 dicella ehrenbergi and PlumateUa repens. — J. Stevens, 

 1, Friar's Walk, Exeter. 



Circulation in Plants. — In reply to the query 

 of Mr. A. C. Smith, there should be no difficulty 

 in seeing this with a good J-inch objective and 

 transmitted light from ordinary concave mirror 

 carefully adjusted. I would recommend him to 

 procure a hair from the stamen of common spider- 

 wort, which should be plunged in alcohol for a 

 second, and then placed on a glass slide in water 

 and covered with a thin glass cover. He should 

 also obtain a thin section from the leaf of the well- 

 known water-plant, Vallisneria spiralis, and prepare 

 and examine in same way. I have known the 

 circulation in the cells of the latter to last for 

 three or four davs. — J. C. Webb, 32, Henslow Road, 

 Diilwich, S.E.; March jth, 1894. 



Circulation in Plants. For the information 

 of your correspondent (Vol. I., New Series, p. 8) 

 who desires to see the phenomenon of cyclosis of 

 protoplasm in the cells of plants, I would re- 

 commend American pond-weed (Anacharis alsicorne), 

 which is now extensively distributed in canals 

 and old ponds, or the Vallisneria spiralis, cultivated 

 in most aquaria. Cut a thin slice longitudinally, 

 and float it on a glass slip, covering with thin 

 glass. Let it stand in a strong light about an 

 hour, and then examine with J-inch to i-inch 

 objectives, when the granules of chlorophvl will 

 be seen rotating within the brick-shaped cells. 

 The stoneworts, Chora and Nitella, are very 

 excellent plants, in which the cyclosis within the 

 long cylindrical cells may be seen with a i-inch 

 objective. Any of these plants, I think, may be 

 had from Mr. T. Bolton of Birmingham. — W. W. 

 Midgely, Ckadwich Museum, Bolton, Lancashire ; 

 Feb. iA,th, 1894. 



Circulation in Plants. — In reply to Mr. 

 Smith's query, I may mention as a capital example, 

 Vallisneria, a small plant purchased from any dealer 

 in aquarium requisites, will answer the purpose 

 admirably. The tip of the leaf is best, as showing 

 the return of the sap, and a young thin leaf is 

 easiest to examine. A moderately high power, say 

 one inch, will show this phenomenon, and a good 

 strong illumination through the object from below 

 is required. I am unable to state the length of 

 time after cutting, for which circulation lasts, it is 

 considerable, however, so long as the leaf is kept 

 well moistened. — E. M. White, 29, Dujfield Road, 

 Derby ; March, 1894. 



Marine Rotifers in Captivity. — In August 

 last a correspondent sent me a four-ounce bottle 

 of salt water from a tidal ditch near Maldon. 

 It contained Brachionus m'ulleri, $ and ? Ptero- 

 dina clypeata in abundance. The first species 

 disappeared at the end of six weeks, while the 

 second is now more numerous than ever. Can 

 anyone suggest a reason for this ? The water is 

 perfectly healthy, being kept so by the quantity of 

 seaweed (Enteromorpha compressus) in it. Do these 

 two rotifers feed on different things, and was the 

 supply of food of one species exhausted ; also why 

 should the larger and stronger die out and the 

 weaker flourish ? — Ernest H. Tugwell, 6, Lewisham 

 Road, Greenwich. 



A Farmer's Microscope. — At the December 

 meeting of the Royal Microscopical Society, Mr. 

 Nelson described a new microscope constructed by 

 Messrs. Watson, specially adapted for the observa- 

 tion of seeds and similar objects under a low power. 

 The two noticeable features are — (1) There is no 

 fine adjustment ; (2) The main stage is very large 

 (4 in. by 4 in.). The hole in the stage is one inch in 

 diameter and can be closed by a sliding plate. The 

 mirror is a silvered equi-convex lens. One lens 

 selected for the instrument is a No. 4 Leitz, giving 

 a power of one hundred diameters with tube extended 

 and sixty-six when closed. The other lens is made 

 on the plan of a Zeiss & with a concave front, but 

 differs from those lenses inasmuch as its aperture is 

 greater. The range of power in this lens is more 

 than twice as great as in the case of a Zeiss &. 

 There is no doubt that this instrument will open 

 up a wider field for research and should prove 

 especially useful to the scientific farmer. — N . Beeman, 

 24, Holborn Viaduct, E.G. 



Entomostraca and the surface-film of 

 water. — At a Meeting in February of the Linnean 

 Society, a paper on this subject was communicated 

 by Mr. D. J. Scourfield, whose main propositions 

 are thus briefly summarised. Many Entomostraca 

 find in the surface-film of water a dangerous element 

 in their environment : this is notably so with many 

 members of the Cladocera and Ostracoda. Con- 

 versely, to some specially modified species of 

 Cladocera and Ostracoda, as well as to some 

 Copepods, the surface-film affords peculiar advan- 

 tages. Except where some Copepods may possibly 

 make use of the properties of the surface-film to 

 attach themselves to aquatic plants above the 

 general water-level, their relation to the surface- 

 film, whether beneficial or the reverse, depends 

 fundamentally upon the same physical principles, 

 namely, the upward pull of the surface-film when 

 forming a capillary depression, and the possession 

 by the crustaceans of water-repellent shells, ridges, 

 scales or seta?, capable of penetrating the surface- 

 film and producing capillary depressions'. 



