546 SUMMARY OF CURRENT RESEARCHES, ETC. 



or False Mole ; " " How to Mount tlie Starches ; " eleven pages of 

 "Editorial Abstracts" and "Selections," witli a column of "Items" 

 (which includes some medical " Facetiae ") and. Reviews. 



Seller's Compendium of Microscopical Technology * — The author 

 of this book is Dr. Carl Seiler, late Director of the Microscopical and 

 Biological section of the Academy of Natural Sciences of Philadel- 

 phia. The various chapters deal with (1) The Microscope and how 

 to use it; (2) Preparation of animal tissues; (3) Cutting sections; 

 (4) Staining of tissues ; (5) Injecting tbe vascular system ; (6) 

 Mounting and finishing of specimens ; (7) The preparation of vege- 

 table tissues and insects ; (8) Photomicrography ; and an Ajipendix, 

 containing a table of tumours. 



The author's object has been (for the most part) not, as is so often 

 the case, to describe a number of methods which have not been 

 actually tried by the writer describing them, but to give a clear and 

 short description of processes which he is in the habit of using 

 himself, and which he has found to give uniformly satisfactory 

 results. 



Smith's ' How to See witli the Microscope.' — This is a book of 

 410 pages and 33 figures (by Dr. J, Edwards Smith, a well-known 

 American microscopist), a more extended notice of which must 

 be deferred until later. In the meantime, we may mention that 

 the leading idea which runs through the book is that of the superiority 

 of wide-angled immersion-objectives, and it has been with peculiar 

 interest that we have read Dr. Smith's remarks having regard to the 

 recent revival of the old views of angular aperture. The author's 

 remarks represent the state of our knowledge at a period which may 

 be said to be half-way between the two extreme points — the j)eriod 

 when no one supposed that wide-angled immersion-objectives could 

 have any excess of aperture, in the proper sense of the term, over 

 dry objectives, and that in which it was at last seen, not only that 

 there was such an excess, but also how it acted. 



Dr. Smith gives some very practical instances of the cases in 

 which oil-immersion objectives exhibit a sujieriority of performance 

 over all others, at the same time considering that the theoretical 

 grounds for this superiority are beyond elucidation. As he puts it : 

 " From a theoretical or mathematical standpoint, the study of balsam- 

 " angles fairly bristles with difficulties ; it has been to us a problem 

 " to which our school-boy wrestlings with Euclid seem a pleasant 

 '• and simple exercise " — as indeed the question was to every one 

 until Professor Abbe established not only the existence of the larger 

 aperture, but also its specific function. 



* Seiler, C, ' Compendium of Microscopical Technology ; a Guide to Piiy- 

 sifians and Students in the Use of the Minioscope, and in the Preparation of 

 Histolotjical and Pathohjgical Specimens.' 130 pp., 1 pi., and IG figs. (8vo, 

 Philadelphia, 18S1.) 



