20 



THE AMERICAK MONTHLY. 



[January. 



series of " Vegetal Esculents and Adulter- 

 ations," which will doubtless have a large 

 sale. They also offer a series of " Textile 

 Fabrics," which it seems would be more 

 properly termed textile fibres, for no woven 

 fabrics are indicated on the list ; and they 

 also have a well-selected " Botanical 

 Series." 



— We notice, in connection with the 

 above remarks, that it is declared in the 

 price-list of Messrs. Spencer & Co.'s ob- 

 jectives, that there is "no discount from 

 this list." Why cannot other makers and 

 dealers adopt the same principle of busi- 

 ness and live up to it ? The trade has been 

 demoralized by some dealers constantly 

 offering discounts, until the impression 

 has spread abroad that anybody can get 

 a discount on any stand if he applies to 

 the right dealer. It is not true, to be sure. 

 If stands and objectives are advertised at 

 their proper value, dealers cannot afford 

 to give discounts, and purchasers will ^ = 

 suspicious if they are offered. 



— A writer in the English Mechanic re- 

 fers to the hirsute covering of paramecium 

 and other infusoria shown when a solution 

 of quinine is added to the water in which 

 they live, although the cilia are quite in- 

 visible when the animals are swimming 

 about. Quinine may prove to be a valua- 

 ble reagent for killing the infusoria and 

 rendering their cilia visible. 



— Our readers will notice that Messrs. 

 •H. R. Spencer & Co. have constituted Dr. 

 H. H. Chase sole agent for the sale of 

 their celebrated objectives. The natural 

 inference is that Messrs. Spencer & Co. 

 intend to devote all their energies to the 

 construction of objectives, leaving all busi- 

 ness affairs to be taken care of by Dr. 

 Chase. We trust the new arrangement 

 will prove satisfactory in every way, as we 

 doubt not it will. 



— Another writer in the same periodical 

 states that the eye of the domestic flea, 

 Pulex irritans, is a most beautiful object 

 when seen with a power of 200 diameters 

 with reflected light. It presents the ap- 

 pearance of " a crystalline lens about 1-500 

 of an inch in diameter surrounded by a 

 dark brown or black rim, and sunk in a 

 depression of the rich chitinous covering 

 of the head. If the light be judiciously 

 applied, this combination of bright light 

 in the lens, with the middle tint of the sur- 

 rounding yellow skeleton of the head and 

 the dark supplied by the black rim, * * 

 presents a combination worthy the study 

 of the trained eye of the artist." The 

 writer goes on to say that the lenticular 



properties of the eye may be demonstrated 

 by obtaining an image from the eye, 

 mounted in balsam, on the stage of the 

 microscope, precisely as is done in the 

 familiar experiment with the beetle's eye. 



NOTICES OF BOOKS. 



A Guide to the Microscopical Examina- 

 tion of Drinking Water : With an Ap- 

 pendix on the Microscopical Examina- 

 tion of Air. By J. D. MacDonald, M. 

 D., R. N., F. R. S., Inspector-General 

 of Hospitals and Fleets, Ex-Professor of 

 Naval Hygiene, Army Medical School. 

 With Twenty-five Lithographic Plates. 

 Second Edition. Philadelphia: P. Blak- 

 iston. Son & Co., 1012 Walnut street, 

 1883. (8vo, pp. 83.) 



We are pleased to see a new edition of 

 this excellent work, the plan of which is 

 well adapted to the needs of those who are 

 not familiar with microscopical work, but 

 have occasion to examine water with the 

 microscope. The classification of the or- 

 ganisms described has been slightly chang- 

 ed since the first edition, and the system 

 extended. The specialist might find some- 

 what to criticise in the arrangement adopt- 

 ed, but for practical purposes it does very 

 well, and, indeed, it would be difficult to 

 improve it. 



The author has aimed to produce a book 

 which will guide the observer, by the aid 

 of plates and descriptive text, and a sche- 

 matic arrangement of the families and 

 genera of the organisms found in water, 

 to a correct determination of t'heir names. 

 In this he has succeeded, we believe, so 

 far as success is possible in the face of the 

 great difficulties involved in the task. 



Report on an Examination of the Exter- 

 nal Air of Washington : By J. H. Kid- 

 der, Surgeon U. S. Navy. (Extracted 

 from the Report of the Surgeon-General 

 of the Navy for 1880. Washington : 

 Government Printing Office, 1882. 

 (Pamphlet, pp. 24, with 10 plates.) 



Exchanges. 



[Exchanges are inserted in this column without charge. 

 They will be strictly limited to mounted objects, and 

 material for mounting.] 



Wanted — American foraminiferal material or slides, 

 in exchange for material or slides of foraminifera from 

 green sand, and other formations or recent species. 

 J. H. HARVEY, 

 St. John's College, Cambridge, England. 



For Exchange — For first-class slides : One Geo. Wale 

 first-class % objective (cost Jio) and two single nose- 

 pieces, made by Schrauer, cost ^3 each. Address 

 W. B. H., Room 27, 24 State street. New York City. 



