fIrst in precision optics

LEITZ STUDENT,..-t,-i..jA;0;;;;;;;;;S,00S,000-Cl00000000000 ffft iViditit0000 ,.,,,,,,,.,,,.,,.,,,,,,,,,,.j...,..,..........

POLARIZINCMICROSCOPE

A reasonably priced, but flexibleand rugged polarizing microscope

for the geology student or chemi-

cal laboratory. This instrument

has polarizing filters throughout,

a built-in auxiliary Bertrond lens,

and will accommodate eyepieces

with large field of view.

Model G-POL $510.00

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A reputation for integrity and a tradition of service have led thousands of scientific

workers to bring their optical problems to Leltz. If you have problems in this field,why not let us help you with them?

See your Leitz dealer and examine these Leitzins4ruments soon. Write for, information.

r -b- - -__E LEITZ, INC., Dept. SC-5

1 468 Fourth Avenue, New York 16, N.Y. II Please send me the Leitz brochure. I

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E. LEITZ, INC., 468 FOURTH AVENUE, NEW YORK 16, N.Y.

D I stri buto rs of t h e wo rl d -f am o u s prod u cts of

Ernst Leitz G. m. b..H.,Wetzlar Germany- Ernst Leitz Canada Ltd.

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NEW SAUNDERS BOOKS-

Romer A Shorter Version of theSecond Edition of The Vertebrate Body

Here is a shorter version of Dr. Romer's outstandingtext, The Vertebrate Body. Designed for short coursesin comparative anatomy, it incorporates all the items 'Helpful Featuresof major interest in the longer work. The first threechapters, which include material on the vertebratebody plan, the historical development of vertebrates coo390 excellent illustrations-ome in Iand a discussion of vertebrate classification, are re- color

produced without change, as are the appendices. Thechapters on the organ systems are approximately Anaomyaoftvertera treat ineahalf as long as the original work. The author givesan interesting account of the functional changes emphasizinghumanstructure

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eventful history. Adequate attention is given to understanding of homology

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r. ~~~~~ . ~~~work retainedBy ALFRED S. ROMER, Alexander Agassiz Professor of Zoology, andDirector, Museum of Comptriative Zoology, Harvard University. 486 pages,

68 x 91/4'', with 390 ilfustrations. $5.50. New.

Carpenter -Immunolo and SerologyThis useful text will provide your students with anup-to-date study of immunological reactions to in-fectious diseases. It clearly explains the properties Helpful Featuresand behavior of antibodies formed within an animalin response to foreign antigenic substances. The V Tables and diagrams quickly translateauthor provides you with helpful tools to assist in the /deabe and iagramsoquipstrclateclassification of bacteria, plants and animals and the ideas and interrelationships-clarify

identification of their components. The book opens test results, reactions and structureswith a presentation of the types of immunity, the

V A 27-page Appendix describes experi-nature of infectious disease, normal protection and / A seroligisusceptibility. Antigens are fully discussed-their de- ments in serology

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the techniques by which antigen-antibody reactions time in explanation.are stuclied in the laboratory. Various serologic re- llustrations are excellent and serve

actions are described briefly in the second chapter.Later the development and identification of each re- well to simplify t-he understanding ofaction are discussed in detail. the subject matterBy PHILIP L. CARPENTER, Professor of Bacteriology, Univesity ofRhode Island. 35 pages, 6S" ax9'A", illustxuecLd$ New.

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PIPETTE WASH ERFor washing pipettes from 125 mm. to 375 mm. byalternately filling and siphoning a cleansing flowover and through the pipettes. The filling andemptying cycle requires about one minute. Auto-matic. Stainless steel. Includes Rack.

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PIPETTE RACKInterchangeable rack fits pipette washer and pip-ette dryer. As an extra rack this stainless steelpipette holder is economical.

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#71-281 -1 ................ $45.00

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more accuracy here-to givebetter results in your lab

Not even one degree variation in temperatureat top and bottom of chamber!

This uniformity (i Y80C.) is a big reason

you'll like Castle's PRECISION INCUBATOR.It gives the accuracy you need and results you can

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Triple-wall construction provides extra-largeheated water jacket, and insulating dead airspace. This maintains even heat inside, keepsover-all chamber temperature to within 120 C.of your setting.

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* LOW PRICE, DOUBLE VALUE! Colorimeter plus spectrophotome-ter, 375mu-950mpu range, precision jack-of-all-work. 49 clinicalcalibrations, *increased range to 340mu.t, available at slightextra cost.

WRITE FOR IMPORTANT DATAFor your free copy of informative Catalog D-266, writeBausch & Lomb Optical Co., 64205 St. Paul St., Roches-ter 2, N. Y. (Obligation-free demonstration on request.)

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America's only complete optical source... from glass to finished product.

SCIENCE, VOL. 123

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SCIENCE, VOL. 123856