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WHAT GENETICS IS

Genetics is the study of the laws governing heredity, and their application to all living creatures. Heredity, in Ribot's definition, is "that biological law by which all beings endowed with life tend to repeat themselves in their descendants; it is for the species what personal identity is for the individual. By it a groundwork remains unchanged amid incessant variation; by it Nature ever copies and imitates herself."

"An exact determination of the laws of heredity," says William Bateson, "will probably work more change in man's outlook on the world, and in his power over nature, than any other advance in natural knowledge that can be clearly foreseen. To gain this knowledge is the object of the science of genetics, which proceeds in practice, largely by means of plant breeding and animal breeding, for the reason that heredity is less complicated in these organisms than in Man, and its operation can be more easily made out. The knowledge so gained finds its application in methods for the improvement of cultivated plants and domesticated animals and, most important of all, in the improvement of the human race through the science of eugenics, which was defined by its founder, Francis Galton, as "the study of agencies under social control that may improve or impair the racial qualities of future generations, either physically or mentally."

THE AMERICAN GENETIC ASSOCIATION

is an incorporated organization, co-operative in nature and devoted to promoting knowledge of the laws of heredity in the broadest sense of the word, and their application to the improvement of plants, animals, and human racial stocks. It is the largest organization in the world for the advancement of genetics, and its organ, The Journal of Heredity, is the most important agent for furthering the interchange of ideas between investigators of different phases of these problems, and for the presentation of their results to the public.

Through its committees on research, co-operation with which is not obligatory, but is urged upon every member, the association collects information by means of approved scientific methods applied to the subject of genetics. This information, as well as that derived from other authoritative sources, it endeavors to place before the public by means of its committee on education and extension, and before its membership, in an attractive and understandable way, through this magazine. The association constantly strives to further the cause of conservative, constructive science and to check the progress of fallacious and sensational pseudo-science. While it can not assume responsibility for the accuracy of statements made by contributors to The Journal of Heredity, it endeavors to publish only such as are on a sound scientific basis, and members are urged to contribute such articles, with illustrations. The magazine does not pretend entirely to cover the immense field of genetics, but it is designed to keep members informed of the latest results in research in the most interesting lines, and to present these results in such a way that they will appeal not only to the specialists, but to the general reader who desires to know what the specialists are doing in a science that is of such personal importance to each individual.

REQUIREMENTS FOR MEMBERSHIP

Membership is composed of scientists, teachers, publicists, physicians, clergymen, students, horticulturists, and breeders of live stock, throughout the world. Subject to the approval of the council, any person interested in the improvement of the human race or the creation of better varieties of plants and animals, is eligible for membership. The secretary will be glad to correspond with those interested, and to send a copy of the magazine for examination. Annual dues, giving the right to attend all meetings and to receive the Journal of Heredity, are $2; life membership is $50. Address all communications to

THE AMERICAN GENETIC ASSOCIATION

511 Eleventh Street Northwest

Washington, D. C., U. S. A.

The

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WIDE RANGE OF VARIATION IN DAHLIAS FROM A SINGLE PLANT

Three flowers of "Spanish Century," the color of which is regularly yellow splashed with red. The three blossoms here shown are from
the same stalk. Variations like this may be due to local conditions or to some change in the germ-plasm; the only sure test of
their nature is that of breeding; if they did not originate in the germ-plasm, they will not reproduce themselves. (Frontispiece.)

SOMATIC SEGREGATION

Variations in Plants May Be Divided in Two Classes, One of Which Breeds True
While the Other Does Not Modern Work Shows Importance of Former
Class in Practical Breeding Further Study May Aid in Under-
standing Causes of Variation in General.1

H

E. J. KRAUS

State Agricultural Experiment Station, Corvallis, Oregon

ORTICULTURAL literature generally, and particularly that which deals with ornamentals, abounds in references to bud variations, bud sports or node sports according to the notion of any particular writer. Anyone dealing with plants in quantity is impressed by the differences exhibited by individuals, differences which often it would be desirable to perpetuate, if possible. It has been argued that, if vegetative propagation means simply the dividing up of an individual into many independent parts, all of which are still the same individual, then the extent to which a plant which possessed particular merit could be multiplied and disseminated, would be limited only by the relative ease of propagation. As a result, considerable work has been attempted along the lines of selection of better strains of many kinds and varieties of plants. Practically the whole idea of pedigreed nursery stock, the selection of runners in strawberries, and the reworking to another strain of unprofitable trees or orchards for greater yields or better fruit, is based on the question of bud variation and bud selection. While the evidence from most of the experiments so far conducted along these latter lines is negative, it is by no means safe to conclude that there is nothing in the idea of improvement by such methods. The greatest difficulty which has arisen and led to confusion has been the failure to recognize the difference between those unstable variations due to purely local conditions and those which, while they may be due to local con

ditions to some extent at least, are a real part of the plant organization and persist even under widely changed environment.

Bud or somatic variations are subject to a broad classification, much as are seminal or seed variations. Three classes are recognizable: modifications (fluctuations), segregations, and mutations. The first class is observed by far the most commonly, and has furnished the material for the larger part of the experiments which have been conducted with an attempt to determine whether superior strains could be built up and maintained entirely by the selection of vegetative parts. The second class occurs in individuals of hybrid, or supposed hybrid origin (the term being used in its broad sense), or in those individuals in which some apparently new character has arisen, but remains associated with the original form and at times exhibits itself wholly independently to a greater or less extent. To illustrate: an example of this latter sort is the manifestation of pure white in the green and white variegation of many plants, or the production of self-colored flowers by certain individuals which normally bear striped flowers. striped flowers. To the third class belong sudden wide changes or departures from the normal character of a plant, such as double flowers, purple foliage, certain instances of the white areas in foliage, fastigiate forms and the like, which apparently are new to that individual. It is difficult, clearly to differentiate the second and third classes, and if one believes that mutations are merely a result of hybrid

Read before the twelfth annual meeting of the American Genetic Association, at Berkeley, Cal., August 5, 1915.

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