180 



THE AMEEICAN MONTHLY 



[Sept., 1880 



cess." We are pleased to extend our con- 

 gratulations to Mr. Skear on account of the 

 encouraging prospects for his magazine, 

 and to assure him of our best wishes for its 

 welfare. The subscription price is $1.50. 



— During the past Summer we have 

 had the pleasure of visiting Professor H. 

 L. Smith at his home in Geneva, and also 

 the celebrated makers of objectives, the 

 Messrs. Spencers. 



At the time of our visit we took great 

 interest in some objectives which Mr. 

 Herbert Spencer manipulated for us. A 

 new ^-inch-immersion, still unfinished, 

 with a rather unfavorable illumination 

 showed the lines on a dry Amphipleura 

 pellncida better defined than we had ever 

 seen them before. To our amateur eye 

 the lens seemed to be very perfect, but 

 the experience of the makers enabled 

 them to observe defects which would be 

 eliminated before the glass was finished. 

 There is no doubt that the Messrs. Spen- 

 cers are constantly trying to improve their 

 lenses, and to make them superior to all 

 others if possible. The means which they 

 have adopted to ensure excellent and uni- 

 form results, by constant personal super- 

 vision of every part of the work and 

 making the final corrections and mount- 

 ings themselves, are sure to be com- 

 mended by all who use the Spencer objec- 

 tives. In passing, we would add that to 

 Mr. Herbert Spencer the credit is mainly 

 due for the present excellence of those 

 objectives. 



— We have been greatly pleased with 

 some of the lenses which Mr. Gundlach 

 has made recently. Mr. L. R. Sexton, of 

 Rochester, who is selling Mr. Gundlach's 

 productions, has kindly sent us objectives 

 for examination, from time to time. 

 Among those we have seen we can highly 

 recommend the |-inch and the ^-inch of 

 class D. The former costs $18.00 and 

 the latter, a glycerin-immersion only, 

 $25.00. It is claimed that the ^^ for 

 $25.00 will resolve the A. pellucida by 

 simple illumination with mirror and lamp. 

 We have not succeeded in this resolution, 

 as yet, but have no doubt it is quite pos- 

 sible, for we have distinctly seen the lines 

 of No. 19 on the balsam test-plate, with 

 one of these tenths. It also works tole- 

 rably well on the Podura-scale. The 

 latest production which Mr. Sexton offers 

 is a >^-inch with a balsam-angle above 

 130°. This has been spoken of by one 

 regarded as excellent authority, as an ex- 

 ceptionally fine lens. The balsam-angle 

 is higher than that of the Zeiss objectives. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted 

 objects, and material for mounting.] 



Lime sand, composed almost exclusively of micro- 

 scopic Foraminifera, to exchange for microscopic 

 material. H. A. GREEN, Atco, N. J. 



I would like to have the address of some person 



who has access to an abundance of Volvox globator. 



W. W. BUTTERFIELD, Indianapolis, Ind. i; 



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. 



Pleurosigmas and other unmounted Diatoms, both 

 Fresh Water and Marine ; also Marine Algse, Ferns, 

 and a large quantity of miscellaneous microscopical 

 material in exchange for good mounted objects. 



M. A. BOOTH, Longmeadow, Mass. 



To exchange, well-mounted Slides of Hair for 

 mounted or unmounted specimens of hair from the 

 rarer animals ; lists exchanged. WM. HOSKINS, 

 208 S. Halsted street, Chicago, 111. 



Nicely mounted Slides (opaque) of the Coal-tar 

 Derivatives, chemically prepared, crystalline in form, 

 showing their beautiful colors, in exchange for other 

 well-mounted material. Chemical name and formula 

 attached to each Slide. About a dozen varieties on 

 hand. F. L. BARDEEN, M.D., 



3oJ^ Meigs street, Rochester, N.Y. 



Slides mounted from injected Frog's Gall-bladder, 

 Liver, Kidney, Stomach, Intestine and other parts, 

 exchanged for other good and interesting prepa- 

 rations. C. BLASDALE, M. D., 



Jericho, Queens Co., N. Y. 



Well-mounted, selected and arranged Diatoms, for 

 good histological, pathological or anatomical prepara- 

 tion. State what you have, and terms of exchange. 

 W. W. RINER, Greene, Iowa. 



The American Monthly Micro- 

 scopical Journal. 



Issued on or before the fifteenth 

 day of each month. 



Correspondence should be ad- 

 dressed to the Editor, Romyn Hitch- 

 cock, 53 Maiden Lane, New York. 



Terms: $1.00 per year; single 

 numbers, 15 c. To foreign subscrib- 

 ers, 63^ francs, or 5 shillings sterHng. 



