20 



THE AMERICAN MONTPILY 



[January J 



cussed at considerable length. Dr. Cur- 

 tis stated that since the appearance of 

 Klein's Atlas, he had devoted some time 

 to the investigation of these statements; 

 that, with high powers, and the object just 

 out of focus, he had seen an appearance 

 something like that illustrated by Klein, 

 and described by Fleming as an " intra- 

 nuclear net-work." When the corpuscle 

 is in true focus its surface presents a 

 granular appearance, of a somewhat regu- 

 lar pattern, like the surface of a rasp- 

 berry. 



The meeting closed with an exhibition 

 of interesting objects. 



GRIFFITH CLUB, MICH. 



The Griffith Club of Microscopy, of 

 Detroit, Mich., is a new organization 

 which we are glad to hear from. We 

 have a report of a paper read at its second 

 monthly meeting by Mr. J. C. Holmes. 

 The paper was on " The Progress and 

 Uses of the Microscope", and is not 

 readily summed up. 



Mr. Holmes' paper was listened to with 

 the closest attention and was highly com- 

 mended by his associates. At its close 

 Prof. E. W. Wetmore, President of the 

 Club, presented the following formula for 

 determining the magnifying power of a 

 microscope : 



1. Divide ten inches by the nominal 

 focal length of the objective ; this will 

 give the magnifying power of the glass. 



2. Divide ten inches by the linear dis- 

 tance between the centers of the field- 

 glass and the eye-glass of the eye-piece. 



3. Multiply these quotients together and 

 you will get a close approximation to the 

 working power of the combination, when 

 used with the standard length (ten inches) 

 of tube. 



To put the above in mathematical form, 

 let F O equal the nominal power of the 

 object-glass : let F I equal the distance be- 

 tween the lenses of the eye-piece; then 100 

 divided by F O multiplied by F I, equals 

 the magnifying power of the instrument. 

 For an instrument with a longer tube, 

 substitute the length of the tube for the 

 first ten inches in the formula. 



After the announcement that Dr. 

 Main, of Jackson, Mich., would, at the 

 ne.xt meeting of the Club, read a paper on 

 his specialty, " Section Cutting," the for- 

 mal session ended. 



SAN FRANCISCO. 



We are obliged to omit from this issue 

 a report of the San Francisco Society. 



Reviews of Books. 



The Microscopist. — A Manual of Micros- 

 copy and Compendium of the Micros- 

 copic Sciences, Micro-Mineralogy, 

 Micro-Chemistry, Biology, Histology, 

 and Pathological Histology. By J. H. 

 Wythe, A. M., M. D. Third edition, 

 with 205 illustrations. Philadelphia : 

 Lindsay and Blakiston. (8vo. Price, 

 $4.50-) 



This is a book of 250 pages, printed on 

 good paper with clear type, and replete 

 with excellent illustrations. It is so well 

 known to microscopists, however, that we 

 need not enter into a detailed review of 

 its contents. There are some portions 

 that should be rewritten to bring them up 

 to date, particularly those which relate to 

 the capabilities of modern objectives ; but 

 in speaking of this we may also add that 

 there is not one single published work, 

 treating of the microscope, which em- 

 bodies the results of recent investigations 

 upon the theory of the microscope, the 

 proper methods of illumination, and va- 

 rious other subjects of theoretical and 

 practical importance. Most of the illus- 

 trations are printed in one or more colors, 

 on full-page plates, thus greatly adding 

 to the good appearance of the book. 



The field covered is a large one, em- 

 bracing all the subjects mentioned in the 

 title, and many others. The work con- 

 tains much that is not usually found in 

 books of a similar character e. g., the 

 micro-chemical tests, and some tables 

 giving the classification of certain animals 

 and plants. 



We believe it is a valuable work for the 

 sreneral student. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge.] 

 Polyzoa, Palates of Mollusca, Foraminifera, Sponge 

 and Holothurian-Spicules, Synapta-Anchors, Chirod- 

 ota-Wheels, Echinus-Spines, Minute Sea Shells, in ex- 

 change for Polyzoa, Foraminifera, Histological and 

 Pathological preparations, etc. Also, a quantity of 

 Sea Shells in exchange for Land and Fresh-Water 

 Shells. 



F. M. HAMLIN, M. D., 



Auburn, N. Y. 



J. J. B. Hatfield. Arsenal Avenue, Indianapolis, 

 Indiana, will exchange Bleached Plant-Sections for 

 good Diatomaceous material. List furnished on ap- 

 plication. 



For fine specimens of Tingis hyalina, send a 

 stamped envelope to 



ALLEN Y. MOORE, 



186 Dodge St., Cleveland, Ohio. 



