MANSFIELD, J. M.-Division of labour among microscopists. [Post.] MATTHEWS' (J.) Simple Revolving Table. Micrometer Scale, A, 1882. 1. History of the National Committee on Micrometry. By R. H. Ward. 3. A study of the Centimetre marked "A," prepared by the U.S. Bureau 4. Rules for the control of the standard Micrometer. Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 178-200. "Monachus."-Microscopic Test Objects. [Supra, pp. 140-1.] Engl. Mech., XXXVIII. (1883–4) p. 341 and p. 431 (1 fig.). MOORE, A. Y.-The Resolution of Amphipleura pellucida. A reply to Dr. Detmers. The Microscope, III. (1883) pp. 201-4. (See also pp. 200-1.) NELSON, E. M.-Microscopic Test Objects. [Supra, pp. 139-40.] Engl. Mech., XXXVIII. (1883) p. 324 and p. 386 (3 figs.). NUNN, R. J.-The Microscope in Medical Gynecology. Sep. repr. from Trans. Med. Assoc. Georgia, 1883, pp. 8-10. PENNY, W. G.-Theory of the Eye-piece. I. The Dispersion of Light. II. Dispersion of Light. Also criticisms by J. A. C. III. Spherical Aberration. Engl. Mech., XXXVIII. (1883) p. 283 (1 fig.), p. 367 (1 fig.), p. 390 (1 fig.). PFAFF'S Mikrogoniometer. Hoffmann's Bericht u. d. Wiss. App. a. d. Londoner Internat. Ausstell. 1876 (1881) pp. 435-6 (1 fig.), p. 738. PLANCHON, J. E.-See Hager, H. POULSEN, V. A.-Botanical Micro-chemistry. Translated with the assistance of the author, and considerably enlarged by W. Trelease. [Supra, p. 91.] xviii. and 118 pp., 8vo., Boston 1884. POWELL, Hugh, Death of. Engl. Mech., XXXVIII. (1883) p. 279, from Times, Nov. 1883; Sci.-Gossip, 1884, p. 17; Journ. of Science, VI. (1884) p. 51. "Prismatique."-Object-glass working, IX. and X. Engl. Mech., XXXVIII. (1883–4) p. 296 (1 fig.), pp. 420-1. REZNER, W. B.-See Vorce, C. M. ROGERS, W. A.-A critical study of the action of a diamond in ruling lines upon glass. [Supra, p. 126.] Proc. Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 149-65. See Micrometer Scale. STOKES, A. C.-A Growing-cell for minute Organisms. [Supra, p. 122.] Sci.-Gossip, 1883, pp. 8-9 (1 fig.). STOWELL, C. H. and L. R.-A new Microscopical Journal. The Microscope, III. (1883) p. 223. [Micrometer which showed Newton's rings in a beautiful manner; also a newly ruled micrometer, each alternate line being ruled longer, so that the end of each band is half the value of the band proper; that is, if the band was in the field ruled 50,000 to the inch, then the end of that band would show 25,000 to the inch. Therefore, as Mr. Fasoldt says, one can easily judge if there is any diffraction.”] C. H.-A Microscopic Inflation. 66 The Microscope, III. (1883) p. 239. [Facetious rejoinder to Dr. O. W. Holmes' statement, supra, as to the size of an enlarged Harvard student.] See Tolles, R. B. T. T.-Microscopic Test Objects. The Microscope, IV. (1883) pp. 10–11. [Points out the error in E. M. Nelson's suggestion, supra, p. 139, that objectives should not be tested by oblique light.] Engl. Mech., XXXVIII. (1884) p. 386. Relation of Aperture to Power in Microscope Object-glasses. [Reply to E. M. Nelson, supra, showing the wide difference between his figures and those of Prof. Abbe.] TETLOW, D.-Microscope. TOLLES, R. B., Death of. Engl. Mech., XXXVIII. (1884) p. 410. Boston Evening Transcript, 28th Nov., 1883. ["Mr. Tolles has been long known for the construction of Microscopes and Telescopes of unusually short focus. He made the highest-power Micro- The Microscope, IV. (1884) pp. 3-4 (T. Barlow); pp. 4-5 (C. H. Stowell); pp. 5-6 (G. E. Blackham). Amer. Mon. Micr. Journ., V. (1884) pp. 10–11 (S. Wells and R. Hitchcock). TÖRNEBOHM, A. E.-Ueber eine Vorrichtung an Mikroskoptischen zur allgemein gültigen Fixirung eines bestimmten Punktes in einem Präparat. (On an arrangement of the microscope-stage for the universal fixing of a given point in a preparation.) [Post.] Neues Jahrb. f. Mineral., 1883, I., pp. 195-6. TRELEASE, W.-See Poulsen, V. A. Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 242–5. WALMSLEY, W. H.-Photo-micrography with dry-plates and lamplight. [Vol. III. (1883) p. 556.] Proc. Amer. Soc. Micr., 6th Ann. Meeting, pp. 59-64 (1 fig.). WHITING, SARAH F.-College Microscopical Societies. WRIGHT, L.-Lantern and Limelight matters. [Comparative optical conditions of wick'd lamps and the limelight— ZENGER, K. W.-See Fischer, G. B. Collecting, Mounting and Examining Objects, &c. Mounting and Photographing Sections of Central Nervous System of Reptiles and Batrachians.* Dr. J. J. Mason describes the methods he employed in mounting the sections from which the plates illustrating his book † were "artotyped." "Both the brain and spinal cord were entirely separated from the body, and, with their membranes, placed in iodine-tinted alcohol until they had acquired a slight degree of consistency-from six to twelve hours. They were then transferred to a 3: 100 solution of bichromate of potash, with a small piece of camphor, in a tightly corked wide-mouthed bottle, and allowed to remain until ready for cutting, renewing the solution every two weeks. The time required for the hardening process varies considerably in different animals, and this variation is more dependent upon the class of animal than upon the relative dimensions of the specimens. For example: on the same day I placed the brain of a large rattlesnake with that of a small salamander in the same bottle, and at the end of six weeks the former was ready for section, whilst the latter was not sufficiently hard until a month afterwards. By thus employing the same reagent in all cases, I have been able to note constant differences in the action of both the hardening and the colouring agent, carmine. Perhaps the most striking illustration of this is furnished by the nervous centres of tailed batrachians, which, while they stain very readily, invariably require about a third more time to harden than specimens from the other orders. Specimens from ophidians stain less satisfactorily than those from any other of the classes which I have studied, while with the spinal cords of alligators, turtles, and frogs failure to obtain good results in this particular is very rare. In all cases the sections have been stained after cutting, injury from excessive handling being wholly avoided by the use of siphon 'Minute Structure of the Central Nervous System of certain Reptiles and Batrachians of America,' 1879-1882, Cf. iii. (1883) p. 910. "The methods of histology have reached a perfection which is building up new departments of knowledge, and among successful pioneers in these labours Dr. Mason will always hold an honoured place for the technical skill with which he brings the reader face to face with the revelations of his Microscope, and for the sumptuousness with which his work is given to the world. No such monograph has previously come under our notice, for the illustrations of a difficult research leave nothing to be desired. . "No words could do justice to the beauty of the plates or the value of the information they convey; and it is not too much to regard this work as opening a new era in research by substituting knowledge of facts of microscopical structure for their interpretation by the hand of artist or author; but we can scarcely hope to see many books so beautifully illustrated. The author's method has the merit of inaugurating a comparison of the minute anatomy of the nervous system by enabling the reader to see the structures which he has discovered as he saw them; and hence the book will always be a valuable work of reference; and it will certainly induce others to hand on the torch of knowledge in a like excellent way."-From Bibliographical Notice in Ann. and Mag. Nat. Hist., xii. (1883) pp. 270-4. tubes to remove the alcohol and washings. For producing transparency, oil of cloves has been used, and the mounting has been done under thin, clear covers, in a solution of Canada balsam in chloroform. All the negatives have been made on glass thoroughly cleaned and lightly coated with a solution of wax and benzole, so that the collodion film, previously made adherent to thin sheets of gelatine, could be safely removed from the plate. The flexible negatives thus obtained are well adapted to the artotype process, and, as they can be indefinitely preserved between the leaves of an ordinary scrapbook, are very desirable for a series of illustrations. In making the original negatives on glass, the wet collodion process,' with the sulphate of iron developer, has been exclusively employed. The prints correspond exactly with the negatives, both in outline and detail. No distortion occurs as in silver printing, in which process the paper is subjected to prolonged washing. In many of the photographs the grey substance appears lighter in shade than the white substance. This appearance is due to a greater degree of transparency of the grey substance in these sections, resulting from the action of the oil of cloves, followed by an increased action of the transmitted light on the sensitive collodion film of the negative, and hence by a thinner deposit of ink over corresponding parts of the positive plates from which the artotypes are printed." With regard to the process employed, Dr. Mason says that after experimenting with various methods he found that satisfactory prints could be made in ink directly upon plate paper, and that these impressions were as perfect in fine detail as any of those obtained by the silver process of printing. The plates (all printed by the artotype process) are as durable as steel engravings. "While a photograph cannot often show all that can be discovered by moro direct microscopic observation with a judicious working of the fine adjustment, high authority has stated, and perhaps correctly, that a good photograph with a low power-say from 3 to 1/2 in.-is a better means of illustrating the anatomical structure of the nervous tissues than hand drawing. Some of the plates with high powers leave much to be desired both in distinctness and tone, and in general it may be affirmed that the same defect as regards distinctness always exists, and for obvious reasons, in photographs of sections with powers much above 1/2 in. In fact it now appears to be established that immersion objectives can never be employed for photographing sectionpreparations with the success that has attended their use for blood corpuscles, diatoms, and similar specimens." Preparing Spermatozoa of the Newt.-G. F. Dowdeswell writes that to prepare the spermatozoa of the newt for the examination of the minute barb discovered by him, the first essential is to get them as nearly as possible in contact with the cover-glass and flat upon it; this requires some care to avoid their drying, by which they are * Quart. Journ. Micr. Sci., xxiii. (1883) pp. 336–9 (1 fig.). materially altered. They may be preserved by several methods, either by treating for twelve to twenty-four hours with a concentrated solution of picric acid, a dilute solution of chromic acid, by Dr. Klein's method with a 5 per cent. solution of ammonium chromate, by iodine, by silver nitrate, or by osmic acid or gold chloride; the latter are convenient as being quicker. He has most usually employed picric acid. For staining glycerine, magenta is the best method, as it stains all parts as strongly as desired. To show the general structure alcoholic carminate of ammonia is the most satisfactory, but it does not stain the barb deeply. Other anilin dyes have not been found to answer so well. * The use of glycerine as a mounting fluid for preparations stained with any of the anilin dyes is at best troublesome,† and sooner or later, in the author's experience, the staining runs and the preparation is spoiled. Solutions of acetate of potash or chloride of calcium have not been found satisfactory, the forms, even of such resistant objects as bacteria, in some cases becoming materially altered by these reagents. With Canada balsam, even when dissolved in chloroform or turpentine, the preparations have not been found to fade, as has sometimes been said to be the case, and as we should have expected; nor, if they are sufficiently washed in alcohol and passed through oil of cloves, will they run. The risk, however, of both fading and running may be entirely obviated by using benzine as a solvent for the balsam, or by employing it undiluted and liquefied by warmth. Killing Hydroid Zoophytes and Polyzoa with the Tentacles extended.-H. C. Chadwick recommends the polyzoon to be placed in a small beaker or clear glass bottle, and allowed to remain at rest for several hours. Now take a dipping-tube drawn out to a very fine point and charge it with absolute alcohol. Having ascertained by means of a pocket-lens that the polypides are fully extended, allow the alcohol to drop very gently from the point of the tube, which should be held just above the surface of the water. The success of the experiment depends largely upon the care with which the first quantity of alcohol is introduced into the water. After the lapse of an hour, if the polypides are still extended, a further quantity of alcohol is added until the quantity reaches 60 per cent. After passing through 75 per cent. alcohol, the specimens may be kept in 90 per cent. of the same until required for mounting. Experiments with alcohol upon hydroid zoophytes were not so successful, but Kleinenberg's picrosulphuric acid solution § gave excellent results. The use of this reagent is attended with much less difficulty than that of alcohol. If the subject of the experiment is a zoophyte, *Magenta cryst. 1 part; glycerine 200 parts; alcohol 150 parts; aq. 150 parts; immerse the preparation in the solution for from two to four minutes, according to the depth of colouring required, and then wash. The method is, add an equal bulk of glycerine to the aqueous solution of the anilin dye used, stain somewhat more deeply than requisite, mount on slide with cover-glass in the staining fluid, which is to be gradually replaced as the water evaporates by plain glycerine. Micr. News, iii. (1883) pp. 333-4. § Cf. this Journal, ii. (1882) p. 867. |