HARD WICKE ' S S CIE JVC E- GO SSff. 



i35 



has provisionally called it Protococcus lugubris. The 

 specific name suggests that even microscopists are not 

 deficient in humour. 



"The American Quarterly Journal of 

 Microscopy."— Since the cessation of the publication 

 of the "Lens," until October, 1878, microscopy in 

 America was only represented by the unpretentious 

 little " American Journal of Microscopy." This, like 

 our own Science-Gossip, aimed at giving accurate 

 information, divested as far as possible of scientific 

 technicalities. It was, however, felt by the leading 

 microscopic workers in that country that a journal of a 

 higher scientific standard was desirable, and some nine 

 months ago the first part of the above-named journal 

 made its appearance. With the exception of a few 

 typographical errors it was well printed and illustrated, 

 and contained much valuable original matter. We 

 have just received the third part and perused its con- 

 tents with much pleasure. The various papers are 

 the productions of men who are well acquainted with 

 the subjects on which they have written. The con- 

 tents may be thus enumerated :— two histological 

 papers : "The Ampulla and Pancreatic Ducts in the 

 Domestic Cat " (continued), by S. H. Gaze ; a case 

 of "Tubercular Meningitis," by P. J. N. Danforth. 

 Two botanical : "The Structure of Ophioglossum," by 

 Prof. M. Harrington; "Dubious Forms of Freshwater 

 Algae," by the Rev. Francis Wolle. Three 

 mechanical: "The Formation of the Paraboloid as an 

 Illuminator " (in which he tells us " How it is Done "), 

 by F. H. Wenham ; "A few Remarks on Angular 

 Aperture and Description of a Universal Aperto- 

 meter," by Prof. H. L. Smith ; Two forms of 

 "Comparators for Measures of Length," by Prof. W. 

 A. Rogers. One on mounting : " Practical Hints on 

 the Preparing and Mounting of Animal Tissues," by 

 Dr. Carl Seiler (continued). One infusorial : "The 

 Simplest Forms of Life," by E. Eyfurth. The two 

 first are perhaps too technical for the general reader ; 

 the remaining papers will, however, be found interest- 

 ing to the microscopical student. Mr. Wenham's 

 paper on the "Formations of the Paraboloid " contains 

 minute directions for the construction of that very 

 valuable accessory. The article commences with a 

 reference to a paper read before the Microscopical 

 Society (now the R. M. S.) in 1856, in which he 

 proposed a right-angled prism, connected to the 

 under surface of the slide by a fluid intermedium 

 which transferred the total reflecting surface from the 

 prism to the top plane of the cover. We quote the 

 following paragraph (p. 187), with which our readers 

 will cordially agree : "It is to be regretted that in 

 this countiy the noble art of mechanical construction 

 should be held in such low esteem as not to be con- 

 sidered a worthy element of education enabling 

 persons to carry their own ideas into practice without 

 being stopped by heavy artisan's bills." We supple- 

 ment this by remarking that it is also to be regretted 

 that but few will take the trouble to learn, even 



theoretically, the principles upon which the micro- 

 scope and its accessories are constructed. Professor 

 Smith's paper will commend itself to those who are 

 interested in the possible angle of aperture of 

 objectives. Those who have turned their attention to 

 micrometric measurements can appreciate the difficulty 

 of subdividing a unit accurately ; we have also the 

 difficulty of obtaining some trustworthy division of 

 the inch, or the centimetre, with which to compare the 

 micrometric divisions, but supposing this obtained 

 we rarely find that divisions on the micrometer are of 

 equal value. Professor Rogers gives a table of 

 measurement of 50 spaces made with the most 

 accurate appliances obtainable, and only in one 

 instance do the errors correct each other, the largest 

 average amount of error was found to^ be x -^§§00 

 inch. For ordinary work the slight errors in the 

 division of the micrometer are not of more importance 

 than an error of ^ inch in the length of a 

 carpenter's rule, but when the value of important 

 evidence (as in ascertaining the source of blood-stains 

 by the average diameter of the discs) depends upon 

 perfect accuracy, our readers will see how necessary it 

 is that our measuring instrument should be absolutely 

 free from error. Dr. Carl Seder's paper is continued 

 from the previous number, and contains some valuable 

 hints on the preparation, staining, and mounting of 

 animal tissues. For the purpose of staining, the 

 writer recommends the sulphindigotate of soda, " the 

 effect of this mode of staining is to leave the nuclei 

 bright red, while the formed material of the cell is 

 slightly tinged with blue. The connective tissue 

 fibres become stained with a deep blue cover, while 

 the blood vessels are purplish and mapped out with 

 surprising distinctness ; epithelium and hair take 

 this staining in a very curious manner, inasmuch as 

 the cells of different ages take different colours, 

 varying from a brilliant emerald-green to purple, 

 violet and olive-green." Excepting in a few 

 special cases, Dr. Seiler prefers a solution of Canada 

 balsam, prepared according to Dr. J. T. Woodward's 

 formula, as follows : "A clear sample of Canada 

 balsam is evaporated either in a water bath by 

 artificial heat, or better by placing it in a shallow 

 dish and exposing it to the heat of the sun until it 

 becomes hard and brittle throughout when cold, and 

 until all odour of turpentine has disappeared when 

 warm. This resinous balsam is then dissolved in 

 warm absolute alcohol to the consistency of thin 

 syrup and filtered through flannel. If by accident 

 the balsam has become brown during exposure, the 

 alcoholic solution may be bleached by exposure to 

 sunlight. 



"The advantages of this material are that it soon 

 becomes hard round the edges of the cover, and can 

 be scraped off to finish the slide ; that it never 

 crystallises, as other resinous mounting media fre- 

 quently do, and that it improves the appearance of 

 the object by age. 



