polarized with electric vector in the vertical plane and. that the "skip distance" marks approximately the Snell angle of total reflection from the Heaviside layer. When Snell's law was incorporated in a Lorentz dispersion formula with one critical frequency, there resulted a relation between the dispersion constants and the height of the Heaviside layer, the skip distance and the wave-length of the radiation. The substitution of observed values into this equation determined the various constants, and with these constants the equation was found to agree with other observed skip distances within the error of measurement. The height of the Heaviside layer above the earth during broad daylight came out about 150 miles and the number of electrons per c.c. 105. These are reasonable values and in accord with estimates of these quantities from other sources. The values do not depend at all critically upon the exact value chosen for the fundamental wave-length, changing only by a few per cent. when this is changed from 120 to 200 meters, for example. The reason for this lies in the nature of the dispersion equation and is brought about by the fact that the wave-length region below 50 meters is considerably removed from the fundamental wave-length. Various facts and details of fading are explainable on the theory. Absorption of the radiation has been considered, as well as the effect of the earth's magnetic field in rotating the plane of polarization of the wave.

A theory of reflection is perhaps scarcely tenable in the form just outlined, for the optical constants of the air in all probability merge gradually into those of the Heaviside layer. As a result of this the radio wave, instead of being sharply reflected at the layer, is bent along a curved path. Without further detail, suffice it to say that this modification of the simple theory may be made and still retain practically the same agreement with the observed skip distances and about the same values of the height and dispersion constants of the Heaviside layer. The theory therefore supplements without disturbance the accepted ionic refraction theory of long wave transmission developed by Eccles, Larmor and others. A. HOYT TAYLOR E. O. HULBURT

NAVAL RESEARCH LABORATORY,
"BELLEVUE," WASHINGTON, D. C.,
JUNE 25, 1925

CROWNGALL IN RELATION TO
NURSERY STOCK1

As far back as records are available to the writ

1 Approved for publication by the director of the Wisconsin Agricultural Experiment Station.

ers, it appears that a large percentage of apple nursery trees propagated by the root grafting method have been affected by enlargements, or overgrowths, most of which ordinarily develop about the union of stock and cion. Much difference of opinion has existed both as to the cause of these enlargements and their effects upon the plants. Following the discovery by Smith and his coworkers2, 3 of the causal relation of Bacterium tumefaciens Smith and Town. to the production of galls, "tumor strands" and "secondary tumors" on various plants, and their demonstration of its parasitism on the apple, the enlargements so commonly found about the unions of apple root grafts have been rather generally attributed to the action of this organism, and the sale of crowngalled apple trees has been prohibited by law in many states. However, in recent studies of crowngall, Riker and Robinson and Walkden5 have succeeded in inducing the development of "tumor strands" and "secondary tumors" only in the region of rapid elongation near the growing points of their experimental plants. This work appears to minimize the potential importance of "tumor strands" and "secondary tumors" in relation to apple nursery stock. In view of the many important gaps in the knowledge of crowngall and of the importance to the fruit industry of the questions involved, various groups and individuals have cooperated in organizing a research project, the aim of which is to investigate certain aspects of the crowngall problem, with special reference to its bearing upon the fruit industry.

6

One of the first lines of work started was an attempt to differentiate crowngall of apple from other

2 Smith, E. F., Brown, N. A., and Townsend, C. O., "Crown-gall of plants: its cause and remedy, " U. S. Dept. Agr., Bur. Plant Indus. Bul. 213, 215 p., illus., 1911.

3 Smith, E. F., Brown, N. A., and McCullock, L., "The structure and development of crown gall: a plant cancer," U. S. Dept. Agr., Bur. Plant Indus. Bul. 255, 60 p., illus., 1912.

4 Riker, A. J., "Some morphological responses of the host tissue to the crowngall organism," Jour. Agr. Res., 26: 425-437, illus., 1923.

5 Robinson, W., and Walkden, H., "A critical study of crown gall,'' Ann. Bot., 37: 299-325, illus., 1923.

6 This project, which is supported financially by the American Association of Nurserymen and individual nurserymen in cooperation with the Iowa State College of Agriculture and Mechanic Arts, and the University of Wisconsin, is being administered by the Crop Protection Institute through a committee consisting of Drs. I. E. Melhus (chairman), G. W. Keitt and M. F. Barrus. Coordinated research programs are in progress at the Iowa State College of Agriculture and Mechanic Arts and the University of Wisconsin.

abnormalities which may be confused with it. A preliminary report on this phase of the work follows: Malformations resembling certain types of crowngall and hairy root have been found at the union of apple root grafts which were made from cions and stocks treated with 1-500 mercuric cyanide, cut with knives dipped in 1-1,000 mercuric chloride, callused in clean sand and planted in steamed soil. Cultural and microscopic examinations failed to reveal the presence of the crowngall organism in these overgrowths. Other experiments have shown that fresh callus on apple grafts is not readily wet by water and have indicated strongly that it is not ordinarily an open infection court for the crowngall organism. These and other field experiments give added weight to the idea, which has been suggested from time to time, that gall-like formations, other than commonly known injuries by nematodes, woolly aphids, etc., may develop on apple nursery stock without the intervention of Bact. tumefaciens.

These and other considerations led us to initiate isolation and infection studies with the aim of determining the presence or absence of the crowngall organism in types of malformation found about the union on rejected nursery stock. Such studies are being made on apple trees which were discarded at the nursery because of malformations at the union (supposedly crowngall). So far, over 175 of these trees from seven nurseries in four states have been examined by making five attempts at isolations by the poured plate method, according to a standardized procedure, from the overgrowth on each plant studied. The technique used failed to reveal the presence of the crowngall organism in any of these plants. The efficiency of this technique was tested at frequent intervals upon crowngalls which had been produced by inoculation with Bact. tumefaciens upon apple nursery stock or by natural infection of peach or raspberry. Of 29 such plants thus studied, 27 yielded the crowngall organism, the identity of which was checked in each case by positive results from inoculation into tomato. The sharpness of differentiation in these results is surprising to the writers. From the nature of the situation, it would seem altogether unlikely that this degree of sharpness of difference will be maintained in further studies of rejected apple trees from various sources, since eventually a greater or less amount of typical crowngall will undoubtedly be encountered on such material. It is worthy of note that none of the malformations thus far encountered in the rejected apple nursery stock submitted to us for these studies were of the "soft gall" type. A more detailed account of this work is in process of preparation.

Of the several working hypotheses which might be advanced to conform with these results, the most promising one appears to be that the malformations dealt with on the rejected nursery trees were not induced by the crowngall organism. This suggests the further hypothesis that these overgrowths were merely incidental to the root grafting method employed in the propagation of this material. They appeared to have been associated in their development with imperfect unions and consequent disturbances in the translocation of water and food. Under these circumstances, from what is known of callus development, such malformations might be expected

NORTHERN CALIFORNIA CONFERENCE ON SCIENCE TEACHING

DR. EDNA W. BAILEY and Mr. Clyde M. Westcott, Pacific Coast members of the Committee on the Place of Science in Education of the American Association for the Advancement of Science, requested the school of education of the University of California to conduct two conferences on the problems confronting that committee. One was held in Berkeley, under the auspices of the summer session, on July 17 and 18; the other will be held at the Southern Branch in Los Angeles on August 3 and 4.

It was planned to make this a small working conference, composed of those who have certain responsibilities with regard to the teaching of science in this state. The plan outlined by Dr. Otis W. Caldwell, chairman of the committee, was used as a basis for the preparation of the program, which follows:

Friday, July 17

9:30 A. M.: General meeting and organization: Chairman, Professor George W. Hunter, Knox College, Galesburg, Illinois. Discussion: "Present situation in science teaching in California. What subjects are taught, where, when, in what year, in what sequence; the training of teachers and the load carried by teachers.'' Leader: Miss Elizabeth Bishop.

2:00 P. M.: Three section discussions-"The science laboratory; planning and equipping. Standard lists, Costs." Leader: Mr. Clyde M. Westcott, head of science department, Hollywood High School; "The synthetic view of science in relation to organization of courses in high school and college.'' Leader: Dr. Richard Holman, assistant professor of botany, University of California; "Science and health: What are the scientific fundamentals essential for health education?" Leaders: Dr. J. N. Force, professor of hygiene, University of California; Dr. Agnes Fay Morgan, professor of household science, University of California; Dr. Richard Bolt, assistant professor of hygiene, University of California.

The date of the conference happened to coincide with the climax of the Scopes trial, and in consequence it received much unexpected and undesired publicity. The conference was well attended and participation in the discussion was general. The following recommendations were unanimously adopted.

The science teachers of northern California assembled in this conference note with interest the following tendencies and needs in the field of science:

The four dominant sciences in the high schools of California are general science, biology, chemistry and physics. Botany, zoology and physiography have been disappearing and there has been a large increase in general science and biology.

There is considerable confusion throughout the state in regard to the desirable sequence of science courses. After considering the tendency in the state and throughout the country, the conference recommends that general science be offered by the junior high schools in the seventh grade and in at least one other year. In the four-year high schools, general science is recommended for the ninth grade. Biology should be given in the tenth grade. It is recommended by the conference that a life science be required of all students in the tenth grade. Chemistry and physics should be offered in the eleventh and twelfth grades.

While there seems to be a greater tendency for students to take chemistry in the eleventh and physics in the twelfth, there is not sufficient reason to limit choice in the order of these two sciences.

There is great need for a definition by the College Entrance Board of the subject of physiology as an advanced science for the third or fourth year of high school.

It is recommended that the university offer two elementary courses in each science, one for those who have had high school work in that subject, the other for beginners.

Many teachers are required to teach science without adequate preparation and many teachers prepared in science are required to teach other subjects. From five to fifty per cent. of the teachers in the different schools of California teach some science, and forty-seven per cent. of the science trained teachers are teaching other subjects in the high school curriculum. The conference urges increased attention on the part of high school principals to the assignment of teachers to subjects in which they are properly prepared.

General science and biology constitute a large part of the science in the high schools of the state. Teachers of these subjects have not had proper training. There is distinct need of help from the university in the form of training in subject-matter used in the two courses mentioned. The conference requests the university to provide adequate preparation, such preparation to include courses from the following fields of science: Chemistry, physics, botany, zoology, biology, physiology, bacteriology, public health and nutrition. (There was a general feeling that earth science should also be included.)

In order that science teachers might be better able to realize the possibilities of science in training young people to meet problems of modern life, it is recommended that an extensive and thorough experimental study be made of the science training needed by the individual living in modern society, the selection and organization of subject-matter, and the choice of methods to be used in order to realize these desired ends.

It is recommended that the commissioner of secondary education of California provide a clearing house for laboratory plans, specifications for laboratory furniture, equipment and standard lists of supplies for each of the courses now commonly given in the secondary schools of the state. Also that copies of such material be prepared and made available to all teachers of science who desire them.

UNIVERSITY OF CALIFORNIA

MABEL B. PEIRSON

Research and Industry in Great Britain; The Asiatic Expedition of the American Museum; The American Public Health Association; Meeting of the American Electrochemical Society; Research Fellows at the Carnegie Institute of Technology

Scientific Notes and News

University and Educational Notes
Discussion and Correspondence:

The Condition of Biological Literature in Paris:
RAOUL M. MAY. Analyzed Sound: PROFESSOR
ALEXANDER FORBES. Loss of Virulence in Fungi:
CARL D. LARUE. Spongilla Lacustris in Massa-
chusetts: W H. COLE and D. POTTER.
Sinister": ROBERT HAWXHURST, JR.

"Bar

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Quotations:

Scientific Men as University Presidents

Scientific Books:

Bigelow's Fishes of the Gulf of Maine: Dr. J. T. NICHOLS

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THE LOS ANGELES MEETING OF THE AMERICAN CHEMICAL SOCIETY

THE Southern California Section of the American Chemical Society were hosts for the seventieth meeting, held at Los Angeles from August 3 to 8, inclusive. More than two hundred made the journey from Chicago on a special train, following a delightful afternoon and evening as guests of the Chicago Chemists Club at the campus of Northwestern University in Evanston. The special train gave an opportunity for enjoying the attractions of Colorado Springs, Santa Fe, New Mexico, Albuquerque and Isleta, as well as the Grand Canyon of the Colorado.

California chemists to the number of twenty-five met the train at Riverside, where after luncheon at the Mission Inn, the party proceeded by auto to the Southland ranch at Corona, where a complete demonstration of the methods used in fumigating citrus groves with liquid hydrocyanic acid gas was given. At the Lemonia grove the party was treated to all sorts of luscious fruits and heard something of the history of the citrus industry in California and something of the operation of the Exchange Lemon Products Company which operates two factories producing citric acid and other products from lemons.

The serious work of the meeting began with the council meeting on August 3. It was announced that the semicentennial meeting of the society would be held in Philadelphia the week beginning September 6, 1926, and that it is expected that the International Union of Pure and Applied Chemistry will meet the following week in Washington. The council unanimously passed the following resolution concerning chemical warfare.

WHEREAS, At a meeting in Geneva, Switzerland, in May and June, 1925, called for an entirely different purpose, a protocol was drafted and signed purporting to outlaw the use of chemicals in war by agreement.

WHEREAS, The Geneva Conference was not only without technical advice on this vital national question of chemistry, but showed in their discussions a la rentable lack of understanding of chemical warfare and the dangers of hasty and ill-considered action, and

WHEREAS, The chemical and military experts in the Washington Conference of 1921 and 1322, after full discussion, recommended that it was against national safety to try to outlaw chemical warfare, which should be considered and controlled in war exactly as any other material or method of waging war; therefore, be it

Resolved, That the American Chemical Society meeting in convention in Los Angeles, California, goes strongly on

record against the ratification of the Geneva protocol on poisonous gases, as against both national safety and on the grounds of humanity.

The council also passed the following resolution offered by the Metric Committee:

WHEREAS, Those scientifically trained find the metric system of weights and measures more convenient to use than the English system; be it

Resolved, that the Council of the American Chemical Society request the manufacturers of photographic plates, films and chemicals to publish approved metric formulas in addition to the English formulas.

Special attention was called to the necessity of reaching an early decision regarding the publication of the second decennial Index to Chemical Abstracts, for which to date insufficient subscriptions have been received to warrant the directors in authorizing the very considerable work involved. Unless a sufficient sum is guaranteed by December 1, the advance subscriptions will be refunded and the project abandoned.

A new section of the society, to be known as the Northern Louisiana Section, with headquarters at Shreveport was authorized, and the name of the Southern Indiana Section changed to the St. Joseph Valley Section at its request.

A. M. Comey, of Cambridge, Mass., was reelected a member of the executive committee. J. F. Norris, professor at the Massachusetts Institute of Technology and now president of the society, and S. C. Lind, assistant director of the Fixed Nitrogen Research Laboratory, Washington, were elected to the board of the Journal of the American Chemical Society. Professor John Johnston, of Yale, F. W. Willard, of the Western Electric Company, and R. E. Wilson, of the Standard Oil Company of Indiana, were reelected to the editorial board of Technologic Monographs. Dr. Charles L. Parsons, of Washington, was reelected secretary for a term of three years.

The next meeting of the society will be held in the spring of 1926 at Tulsa, Okla., followed by the semicentennial meeting in September of that year at Philadelphia. The section at Richmond, Va., will entertain the society in the spring of 1927 with Detroit as the meeting place in the autumn of 1927.

At the general meeting open to the public, Alexander Findlay, of Glasgow, delivered an address on "The twilight zone of matter," and W. R. Whitney, of the General Electric Company, gave an unusual address on "Matter-is there anything in it?" profusely illustrated with special experiments arranged for the occasion and performed with apparatus taken to Los Angeles for the purpose.

Owing to the distance and the difficulty of arranging extended programs under the circumstances, sev

eral divisions and sections met jointly. The Divisions of Agricultural and Food Chemistry and of Biological Chemistry held a symposium on Chemistry and Plant Life, of which Charles D. Lipman, of the University of California, was chairman. The papers dealt principally with energy relations and physiological processes in plant metabolism and were followed by a group of papers dealing with the properties of starches, plant sterols, the activity of plant enzymes and the influence of certain chemicals upon plant growth and development. The general program of these divisions dealt with plant chemistry, human and animal nutrition, the chemistry of casein and the coagulation of milk.

The Insecticide and Fungicide Symposium was under the chairmanship of George B. Gray and considered petroleum insecticides, sulfur-oil combinations, the arsenates, the use of potassium xanthate as a soil insecticide, and the absorption of hydrocyanic acid. for dried fruit products.

The Division of Sugar Chemistry joined the Divisions of Agricultural and Food and Biological Chemistry in a Pectin Symposium of which W. H. Dore was chairman. The need of uniform nomenclature on pectin was stressed and a committee appointed to study the situation and make recommendations. In the course of the symposium various phases from the composition of pectin to its manufacture and the requirements of pectin for the commercial jelly-maker were discussed.

The joint meeting of the Division of Chemical Education with the Section of the History of Chemistry attracted a large attendance, particular attention being given to a discussion of "What are our objectives in teaching chemistry?" This involved a discussion of the methods of presenting chemistry. One speaker stated the chief objective to be to teach the student how to get the facts rather than the facts themselves; another that the laboratory must be made a place for thinking instead of mechanical test-tubing, and that the scientific method must be closely followed in presenting the subject of chemistry. Another speaker insisted upon personal contact with the student as the prime essential, believing that most of the instruction should be given in the laboratory. In the discussion vigorous objection was made to the suggestion that it is at all possible to measure in percentages the gain or loss of intellectual processes. Both fact and ideas are necessary for the advancement of science, but to attain this it is doubtful if standard tests are advisable, since such tests are too apt to overshadow the real value of the subject.

The symposium was followed by a number of papers on various phases of the teaching and the history of chemistry.