144 THE AMERICAN MONTHLY [June, 



Chapter II is devoted to inorganic constituents ; Chapter III, to vege- 

 table constituents, and Chapter IV, to animal constituents. Chapter 

 V presents an interesting and instructive treatise on micro-organisms, 

 showing patient study and extended research. Chapters VI, VII, VIII, 

 discuss water supplies, natural purification, and artificial purification, 

 and Chapter IX describes clearly eight different systems for central fil- 

 tration. An appendix divided into two sections closes the book. Sec- 

 tion A treats of the origin and home of cholera. Section B presents 

 four simple qualitative tests for impurities in drinking water. 



The importance of the subject will appeal to all intelligent readers, 

 especially such as have in any way to deal with zymotic diseases. 



SUBSCRIBEBS' NOTICES. 



[These notices will be given six insertions in this column at 25 cents per line or fraction thereof.] 



WANTED.— Vol. VII, No. 2 (Feb., 1886), of American Monthly Microscopical Journal. 



A. G. YOUNG, State House, Augusta, Me. 



WAN'l'ED. — Diatom material from America, Australia, and Asia in exchange for fossil and recent 

 material from Denmark. ■* 



CHR. MICHELSEN, 33 Nedergade, Odense, Denmark. 



FOR EXCHANGE. — Slides of diatoms from peat bogs in Boston, Mass. 



F. F. FORBES, Brookline, Mass. 



WANTED. — Vol. 1, American Monthly Microscopical Journal. 



C. K. WELLS, Marietta, Ohio. 



WANTED TO PURCHASE. — Histological slides from normal tissues of mammals, prepared with 

 a view to show the size of the " cells," in cases where the age of the animal-subject is definitely known, 

 as bearing on the question of a supposed diminution in the size of cells in aging organi>;ms, correspond- 

 ing to a similar decrease, reported by Balbiani and Maupas in aged unicellular life. Address, 



C. A. STEPHENS' LABORATORY, Norway Lake, Maine. 



WANTED. — Diatomaceous material of good quality, fossil and recent. I offer diatom slides or 

 photo-micrographs in exchange. 



D. B. WARD, Poughkeepsie, N. Y. 



OFFERED. — Diatomaceous Earth from Utah (Desert) for Histological Mounts. 



PROF. ORSON HOWARD, Salt Lake City, Utah. 



WANTED. — Any works on Microscopy not already in my Library. 



H. M. WHELPLEY, F. R. M. S., St. Louis, Mo. 



First-class Histological Slides for other good mounts ; Histological and Pathological material cut on 

 shares. S. G. SHANKS, M. D., 547 Clinton Ave., Albany, N. Y. 



FOR SALE OR EXCHANGE. — Mosquitoes, male and female. Price 75 cents each. Will ex- 

 change only for first-class mounts. E. W. SHARP, 2800 Richmond St., Philadelphia, Pa. 



A $5 MICROSCOPE. — Made on proper scientific principles. Magnifies 100 diameters or 10,000 

 times. For other interesting articles send for list of Popular Scientific Specialties. 



G. S. WOOLMAN, 116 Fulton St., New York. 



SPECIAL BARGAIN in histological slides. 



WM. N. BEGGS, M. D., 2207 Sidney St., St. Louis, Mo. 



FOR SALE OR EXCHANGE. — Photo-micrographs of P. angulatum taken through Spencer's 

 AH. I., 2400 diameters. Also photo-micrographs of bacteria, diatoms, etc.. 25 cents each. Will ex- 

 nange for well-mounted slides. Dr. J. E. BAKER, Wyoming, Ohio. 



TO MICROSCOPISTS. — After July i the price of my well-known slides will be the uniform one of 

 50C. each, ;j(5.oo per dozen. Send 2c. stamp for catalogue and soc for slide of Podura scales, test, or 

 other diatoms, or of miscellaneous objects. Thum's " t_h. My !" slides of arranged diatoms, gorgeous 

 butterfly scales, etc., at lowest rates. 



M. A. BOOTH, F. R. M. S., Longraeadow, Mass. 



