SCIENCE-GOSSIP. 



251 



the subject and of the work which has been done in 

 it. The author comments on the fact that general 

 works on ornithology have become fewer in the 

 following manner : " On reviewing the progress of 

 ornithology since the end of the last century, the 

 first thing that will strike us is the fact that general 

 works, though still undertaken, have become pro- 

 portionately fewer, and such as exist are apt to 

 consist of mere explanations of systematic methods 

 that have already been more or less fully pro- 

 pounded ; while special works, whether relating to 

 the ornithic portion of the fauna of any particular 

 country, or limited to certain groups of birds — 

 works to which of late years the name of " mono- 

 graph " has become wholly restricted — have become 

 far more numerous But this seems to be the 

 natural law in all sciences, and its cause is not far 

 to seek. As the knowledge of any branch of study 

 extends, it outgrows the opportunities and capabili- 

 ties of most men to follow it as a whole ; and since 

 the true naturalist, by reason of the irresistible 

 impulse which drives him to work, cannot be idle, 

 he is compelled to confine his energies to narrower 

 fields of investigation." 



The Story of Forest and Stream. By James Rod- 

 way, F.R.A.S., F.L.S. 202 pp., and 27 illustra- 

 tions. (London : George Newnes, Limited, 1897.) 

 Price IS. 



This useful little work is one of the same series 

 as "The Story of the Plants," by Grant Allen. 

 The illustrations, which are very good, are chiefly 

 of trees, plants and scenes of the tropics, as the 

 author considers that the struggle and changing 

 conditions of plant life are better portrayed in the 

 luxurious growth of a warm climate than in Eng- 

 land. Mr. Rodway has given a clear and interest- 

 ing account of the work done by trees in large 

 forests, carefully describing their use as well as 

 beauty. 



The Photographer's Exposure Book. By Frederick 

 William Mills, F.R.M.S. (London : Dawbarn 

 and Ward, Limited.) Price is. 



This is a handy little note-book with valuable 

 tables arranged in the orders of the months of the 

 year, showing the length of time necessary for the 

 exposure of the plate in various conditions of 

 weather. There are also a number of pages for 

 notes to be taken at the time of photographing ; 

 these are ruled in sections, to facilitate regularity 

 of procedure and comparison. 



Everybody's Medical Guide. By M.D. 122 pp. 

 (London : Saxon and Co.) Price is. 



This is a small guide to the lighter ailments of a 

 household, giving the symptoms by which they 

 may be easily recognised, and some simple remedies. 

 It contains some useful suggestions for the main- 

 tenance of health, extracts from the laws relating 

 to infectious diseases, and the charges usually 

 made by medical men, together with other pieces 

 of information which are likely to be of great use 

 to the heads of households. 



Elementary Botany. By W. Bland. Parts i. 

 and ii., 152 pp., 8vo, 240 illustrations. (London : 

 Bemrose and Sons, Limited.) Price is. 



The first part of this useful little work treats of 

 structural and systematic botany, and the second 

 of vegetable anatomy and physiology. The work 

 is arranged in courses of lessons suitable as the 

 groundwork for lectures. Teachers taking an 

 elementary class in botany would probably find it 

 of use. 



MICROSCOPY 



Preservation of Microscopic Specimens. — 

 In the " International Journal of Microscopy and 

 Natural Science " for January, 1897, an account 

 is given of a method of preserving microscopic 

 specimens of organs and tissues so that they retain 

 the colour they had when fresh. ^NI. Tores, after 

 testing it for a year and a-half, finds it successful. 

 He found that five to ten parts of a forty per cent, 

 solution of formalin caused the organs after a time 

 to assume a tint which differed very considerably 

 from the natural colour, but if instead of water for 

 diluting the commercial formalin solution, a solution 

 of one part common salt, two parts of magnesium 

 sulphate and two parts sodium sulphate in one 

 hundred parts of water be used, the colour of 

 the blood is well preserved. Objects preserved in 

 such a solution are better adapted for microscopic 

 examination, as the protoplasm of the cell is less 

 altered and the nucleus stains more deeply. — F. 

 Winstone, Ockeridge, Epping. 



Acacia as a Popular Micro-Object.— The 

 sprays of Acacia [raccmosa?) sold just now in the 

 London streets and elsewhere for button-holes and 

 flower-vases, furnish quite a budget of interesting 

 objects for the microscope. The small branches 

 usually have several of the pretty whitish-green 

 feathery leaves, and at the end a spray of bright 

 yellow balls of many closely-set flowers. The 

 whitish-green colour is caused by a layer of 

 granules of wax which cover the surface of both 

 stalks and leaves, and by a felty layer of small white 

 hairs on the former. These should be examined 

 opaque with a one-inch or half-inch objective, and 

 light thrown on by bull's-eye condenser. At the 

 base of the leaf-stalk or petiole a swelling is 

 observed, the pulvinus : its purpose is to raise 

 and lower the whole compound leaf in accordance 

 with suitable external conditions. It is more 

 developed in the well-known "sensitive plant," 

 closely allied to this species. At the base of each 

 pinnate leaflet there is a similar but smaller organ. 

 To show the structure, cross-sections should be 

 made and compared with others from another part 

 of the stalk. On the upper surface of the petiole, 

 between each pair of leaflets, is a small gland, 

 almost globular, with a minute opening at the 

 apex, often filled with a secretion, which probably 

 gives rise to the pleasant balsam-like smell of the 

 plant ; they are covered with small closely-set hairs, 

 and form interesting and pretty opaque objects for 

 a low power. The flower-heads will repay careful 

 examination. Space forbids more than mention of 

 the many bright yellow anthers, the crystalline 

 filaments, and the compound pollen, formed of 

 several — about sixteen — simple grains adhering to 

 each other, an arrangement which, though occur- 

 ring in other plants, is not very common. The 

 hairy, almost bristly, bright-coloured calyx, and 

 the delicately-tinted petals, together form a 

 beautiful miniature regular flower, very different 

 in appearance from our native papilionaceous 

 examples of the natural order Leguminaceas.— /as 

 Burton, g, Agamemnon Road, West Hampstead, N. IV. 



