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Apparatus for Magnetic Precision Measurements
The Fahy Permeameter
The Fahy Permeameter
The Magnet-Meter An instrument developed for the precise and rapid investigation of shaped permanent magnets, such as used in magnetos, electrical measuring instruments, etc. This instrument serves to determine not only the initial strength, but also the stability of magnets.
Write for descriptive literature
HERMAN A. HOLZ
Apparatus of High Quality for Magnetic and
Metallurgical Testing and Research Work Metropolitan Tower
Marine Biological Laboratory
Woods Hole, Mass.
INVESTIGATION Facilities for reseach in Zoology,
Embryology, Physiology and BotEntire Year any. Seventy-six privato labora
tories, $100 each for not over three months. Thirty tables are available for beginnersin research who desire to work under the direction of members of the staff. The fee
for such a table is $50.00. INSTRUCTION Courses of laboratory instruction
with lectures are offered in InverteJuly 2 to August 12, brate Zoology, Protozoology. Em1919
bryology, Physiology and Morphology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $50. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is
also offered. SUPPLY Animals and plants, preserved, liv
ing, and in embryonic stages. PreDEPARTMENT served material of all types of
animals and of Algae, Fungi, LiverOpen the Entire Year worts and Mosses furnished for
classwork, or for the museum. Living material furnished in season as ordered. Microscopic slidesin Zoology, Botany, Histology, Bacteriology. Price lists of Zoological and Botanical material and Microscopic Slides sent on application. State which is desired. For price lists and all information regarding material,
address GEO. M. GRAY, Curator, Woods Hole, Mass. The annual announcement will be sent on application to The Director, Marine Biological Laboratory, Woods Hole, Mass.
Two NEW VOLUMES IX THE UNIVERSITY OF
CHICAGO PRESS SERIES The Living Cycades By CHARLES JOSEPH CHAMBERLAIN
Professor of Botany in the University of Chicago
This study includes investigations extending over a period of fifteen years, that necessitated trips to Cuba, New Mexico, Australia, and Africa. The author studied all the genera and many of the species in the field, and preserved much material for later study in the laboratory. In addition to the data presented, the author gives an account of some of his experiences while on his tours of investigation. 186 pages, cloth; $1.50, postage extra
(weight 14 oz.)
By FRANK R. LILLIE
of Chicago A subject which has important bearings upon the problems of heredity and close relations to several fundamental biological problems. This volume is a popular presentation of the subject.
Cloth, $1.75, postage extra
Press 5811 Ellis Avenue Chicago, Illinois
Langmuir Condensation Pump
Dr. Irving Langmnir (of the
than 0.1-0.15 mm.of meroury, The illustration shows a Langmuir pamp, connected to a two-stage primary oil pump—which is operated by a HP motor ; all three parts of the outfit being assembled together on one base. JAMES G. BIDDLE
If interested, write for copy of illustrated 1211-13 ARCH STREET
Bulletin 881, issued November, 1917 ; PHILADELPHIA
and also copy of paper by Dr. Langmuir.
SERVICE With the liquidation of the extensive Government Contracts, which we received during the war period from the Medical Departments of the U. S. Army and Navy, we now find ourselves in a position to offer our service in a prompt and unrestricted manner.
Our binding guarantee accompanies everyone of Haemacytomeler complete with FEi double chamber the Flei Blood Counting Apparatus and Flei Blood Pipettes as well, that their accuracy conforms to the specifications established by the U. S. Bureau of Standards. Test Certificates are furnished upon request.
No. 27679 Marked improvements have been accomplished in both method of manufacture and control of the degree of fineness of the mass in the Mandler Diatomaceous Filters. Several of the largest manufacturers of biologicals in the U. S. using these Filters in very large quantities now report them as distinctly superior to those previously imported. 27689. FILTER CYLINDERS, MANDLER DIATOMACEOUS, with metallic headpiece, fitted
with lock nut, two rubber washers and one fibre washer as required for use in glass
10 x 2
8x13 8x1 5x1 2 x
1.15 10% Discount in case of
72 144 144 27678. FILTER CYLINDER, MANDLER DIATOMACEOUS, 10 x 2 inches, with glazed porce
lain headpiece and nipple, for filtering acids, etc., Furnishe l in one size only.
3.50 10% Discount in case of
24 27679. FILTER CYLINDERS, MANDLER DIATOMACEOUS, with metallic headpiece with
specially long nipple. Furnished with lock nut, two rubber washers and two fibre
74 x 2 6x2 Each . .
3.15 3.00 10% Discount in case of .
24 30 Complete descriptive pamphlet sent upon request
Prices subject to change without notice
ARTHUR H. THOMAS COMPANY
IMPORTERS - DEALERS-EXPORTERS LABORATORY APPARATUS AND REAGENTS WEST WASHINGTON SQUARE
PHILADELPHIA, U, S. A.
THE BOTANICAL OPPORTUNITY1 When this program was arranged, it was in tended to bring to the attention of botanists how they could serve the nation in the crisis of
Committees had been multiplied to do various kinds of necessary work. The results were not all that we had hoped for, but botan. ists were beginning to find themselves, and organization was gradually becoming more effective, because the spirit of cooperation was developing. Enough results were obtained to prove that botany could be of great service at a time of national need. The practical results were not so conspicuous to the public in the immediate activities of the war as those of chemistry and physics for example, but they were fundamental and far-reaching, looking to future as well as to present needs. We must recognize that to bring into effective cooperation great numbers of isolated, scattered, and sometimes conflicting units, takes time and a great controlling motive. But we were making progress, not so rapid as the impatient desired, but probably as rapid as human nature permitted.
Now that the emergencies of war have passed, shall we stop this kind of progress? I wish to attempt to answer this question. In doing so, I shall not formulate any plan, any scheme of organization, but shall present in brief general statement what seems to me to be our opportunity. The other speakers upon the program will doubtless present more concrete suggestions, for which I hope my statement may be an appropriate background.
In connection with the period of reconstruction, there has come to the science of botany a great opportunity, and botanists must rise to the occasion. It is a critical time for our science, for we may lapse into our former state and become submerged by more aggressive
1 Invitation paper before the joint meeting of botanists at the Baltimore meeting of the American Association for the Advancement of Science.