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of continuous selection in corn for certain special characteristics, including both chemical and physical properties, have been carried on for many years at the Illinois Agricultural Experiment Station. Twenty-four generations of selection to influence the composition of the grain show very marked responses, and from a single original variety four diverse strains have been established, namely, high protein, low protein, high oil, and low oil. Similarly, high- and low-ear strains as well as erect- and declining-ear strains have been produced. Another example of this response to selection has been the development of a two-eared strain from an ordinary single-eared variety. In like manner differences in yield have been induced by similar methods of selection. These results all go to show something of the possibilities of profoundly modifying various characteristics by con.

of shelled corn per acre of the F, cross over the better parent has averaged less for the last two years than for the first four years of the tests in the case of crosses with Minnesota No. 13. On the basis of these results it appears that, if corn were selected primarily on the basis of yield, the value of F, varietal crosses would be somewhat questionable.

Rust and the weather: H. L. WALSTER, At Fargo, N. D., blue stem spring wheat averaged 7.1 bushels per acre in 5 seasons when rust epidemics occurred, and 26.7 bushels per acre in 5 nonrust seasons. The average minimal and maximal temperatures by 10-day periods from the date of seeding show the following differences as between the respective 5-year periods: Average Differences in Degrees F. for Each 10

day Period after Seeding. Five-year Averages

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During rust years maximal temperatures rose more rapidly and reached their highest point sooner than in non-rust years. The average rain. fall during April, May, June and July averaged higher in rust years than in good years. When high rainfall occurred in good years danger of rust has been offset by low temperatures. When excessively high temperatures have occurred in good years, danger of rust has been offset by droughty conditions,

P. E. BROWN, Secretary-Treasurer

tinuous selection in a cross-fertilized plant such as corn.

First generation corn varietal crosses: FRED GRIFFEE. A brief review is made of the development of the theory which accounts for the increased vigor of F, crosses. Experiments are reviewed in which F, corn crosses are compared with their parents for yield of grain. Of 146 crosses, 113 exceeded the parental average in yield of grain and 84 exceeded the better parent. At the Minnesota station 5 Aint-dent crosses tested for a period of two to six years yielded an average of 7.7 per cent. more shelled corn per acre than either parent. Particular attention is called to the cross between Minnesota No. 13 and Squaw Flint which yielded 8.4 per cent. more shelled corn per acre than Minnesota No. 13, which is the higher yielding parent, and was a week to ten days earlier in maturity than Minnesota No. 13. Such a cross appears of considerable promise for sections where early maturity is an important factor. During the first three years of the study a strain of Minnesota No. 13 was used which had been selected for type for several years. In the latter years this strain was selected primarily for yield. The increase in yield

SCIENCE

A Weekly Journal devoted to the Advancement of Science, publishing the official notices and proceedings of the American Association for

the Advancement of Science

Published every Friday by THE SCIENCE PRESS LANCASTER, PA.

GARRISON, N. Y. NEW YORK, N. Y. Entered in the post-office at Lancaster, Pa., u second dan matter

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Johns Hopkins University Tulane University of

Louisiana

Medical School
The Medical School is an Integral part of the University and
is in close Affiliation with the Johns Hopkins Hospital
ADMISSION

SCHOOL OF MEDICINE Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction, including laboratory work, in Chemistry, and one year each in

(Establishod in 1834) physics and biology, together with evidence of a reading knowl- ADMISSION: All students entering the Freshman edge of French and German,

Each class is limited to 90 students, men and women being Class will be required to present credits for two admitted on the same terms. Except in unusual circumstances, years of college work, which must include applications for admission will not be considered after July 1th

Chemistry (General and Organic), Physics and Il vacancies occur, students from other institutions desiring advanced standing may be admitted to the second or third year Biology, with their laboratories, and at least provided they fulfill all of our requirements and present ex- one year in English and one year in a modern coptional qualifications.

foreign language. INSTRUCTION

COMBINED COURSES: Premedical course of two The academic year begins the Tuesday Dearest October 1 and closes the third Tuesday in June. The course of instructon,

years is offered in the College of Arts and occupies four years and especial emphasis is laid

upon prao- Sciences, which provides for systematic work tical work in the laboratories, in the wards of the Hospital and leading to the B.S. degree at the end of the in the Dispensary. TUITION

second year in the medical course. The charge for tuition is $250 per annum, payable in threo instalments. There are no extra fees except for rental of microscope, certain expensive supplies, and laboratory breakage.

School of Pharmacy, School of Dentistry and The annual announcement and application blanks may be Graduate School of Medicine also. obtained by addressing the Dean of the Johns Hopkin, Medica School

Women admitted to all Schools of the Washington and Monument Sts. BALTIMORE, M.D

College of Medicine
SUMMER WORK FOR GRADUATES
IN MEDICINE

For bulletins and all other information, address Beginning Tuesday, June 6th, and ending, Thursday, July 16th, a course in medical diagnosis, including laboratory exer

Tulane College of Medicine cises in clinical pathology and demonstrations in pathological anatomy, will be offered. The course will be limited to twenty

P. O. Box 770 students, fee $100. Applications should be made to the Dean's Office.

New Orleans, Le,

Yale University SCHOOL OF MEDICINE

Marine Biological Laboratory

Woods Hole, Mass. INVESTIGATION Facilities for research in Zoology,

Embryology, Physiology, and Bota Eotire Year any. Eighty-four private labora

tories, $100

each for not over three months. Thirty tables are avail. able for beginners in 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 Inverteune 29 to August 9

brate Zoology, Protozoology, Em

bryology, Physiology and Morph1921

ology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $75. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is

also offered. SUPPLY Animals and plants, preserved, live DEPARTMENT

ing, and in embryonic stages. 'Pre 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. Liring material furnished in season as ordered. Microscopic slides in 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.

Affiliated with the New Haven Hospital
and New Haven Dispensary

109th Session

Reorganized on a full-time basis Entrance Requirements : A minimum

of two years (or its equivalent) of college including general biology, physics, general and organic chemistry, physical chemistry or laboratory physics, and either French or German. ALL OF THE GENERAL FACILITIES OF THE UNIVERSITY ARE AVAIL.

ABLE TO MEDICAL STUDENTS As the number admitted to each class is limited, applications must be made before June 15.

Dean, Yale University School

of Medicine NEW HAVEN, CONN.

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For service that requires exceeedingly “fine" and uniform current regulation, we offer the following rheostats: Normal Approximate

Approximate No. Rating Range of

Dimensions of

Over-all

Net
Watts Resistance

Carbon Blocks

Dimensions

Prices 10 250 .06—6 ohms 50 blocks " thick 153" long 41" wide

11 square

51'' high

$12.50 20 1000 .04–4

65 blocks 3" thick 20'' long, 51' wide
2' square

$25.00
30 1500 .01-2
60 blocks t" thick 22" long 77" wide

6'' high

$50.00 3'' square

7}" high 40 3000 .005—1 60 blocks" thick 22"' long gy wide

Price on 4" square

g" high

application * This rheostat is supplied with three movable terminal plates, as shown in the picture.

Write for Bulletin No. 937, describing Jagabi" Laboratory Rheostat JAMES G. BIDDLE 1211-13 ARCH ST., PHILADELPHIA

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Instructor's Desk, No. 1401

Physics and Chemistry.

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You can't afford to compromise Laboratory_Furniture, particularly when America's Best costs but little more in initial investment. In the long wear and tear, it costs less.

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Kewaunee Laboratory Furniture covers the needs of teachers of Physics, Chemistry, Biology, Zoology, Domestic Science and Art, Manual Training, Electricity and Physiography. For complete information, address the factory, at Kewaunee.

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Registers directly-temperature, relative humidity, maximum vapor pressure, maximum capacity of water vapor of c.c. of air, the Hygro number, the dew point temperature, etc.

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