mosomes are found associated in pairs distributed over a network. The further history of the reduction mitoses is not described, so that the investigation is incomplete in a number of important features. The second paper of Rosenberg1 deals with Crepis virens, one of the Composita, a form remarkable for the small number of chromosomes, which are six for the sporophyte and three for the gametophyte generation. A further important peculiarity is a difference in the size of the chromosomes which makes it possible to follow the individual elements through succeeding mitoses with some degree of certainty. This is, so far as the reviewer is aware, the first account for plants of such a differentiation of chromosomes as has been described for animals by a number of zoologists. The nuclei of the sporophyte (somatic) show six small prochromosomes in the resting stage from which are organized during the prophases of the vegetative mitoses two short rod-shaped chromosomes, two very long bent elements, and two chromosomes about midway in length between these extremes. The resting nuclei of the pollen mother-cells have six prochromosomes more or less clearly grouped in pairs. Synapsis presents a series of parallel threads intimately united at intervals. From this condition a thick coiled spirem is organized which clearly shows its double nature in the frequent longitudinal separation of portions as though it were split. The free ends of the chromosomes composing the spirem may at times be distinguished. A gradual contraction of the spirem leads through stages comparable to those described as a second contraction by various authors to the period when the six chromosomes, grouped in three pairs, may be clearly recognized (diakinesis). The chromosome group on the approach of the heterotypic mitosis consists then of a pair of small, almost spherical, chromosomes, a pair of long rods, and a pair of short rods. These correspond to the three different sizes of chromosomes present in the vegetative sporophytic mitoses, but are more condensed or shortened. Thus the heterotypic mitosis is a true reduction division distributing the six chromosomes in two sets each of which consists of a spherical chromosome, a long rod, and a chromosome intermediate in shape between these two. These Rosenberg, O., "Zur Kenntniss von den Tetradenteilungen der Compositen," Svensk Bot. Tidsk., III, p. 64, 1909. chromosomes divide during the anaphase of the heterotypic mitosis in preparation for the second or homotypic mitosis so that they appear at the poles of the heterotypic spindle in the form of three split chromosomes or pairs. The chromosomes change their form in the interkinesis, becoming long spiral threads which shorten on the approach of the homotypic mitosis when the six chromosomes again appear as three pairs showing the same characteristic range of form. The members of these three pairs are distributed by this division so that the nucleus of each pollen grain receives three chromosomes, a short, a long, and a middle-sized element, and these may be recognized in the resting nucleus by three prochromosomes. A brief examination of the mitoses in the embryo-sac supported the conclusions above outlined. BRADLEY M. DAVIS. An Account of Some Modern Methods of Astrophysical Research By GEORGE ELLERY HALE The introduction of photographic methods, the improvement of telescopes, and the rapidly increasing appreciation of the value to astronomy of physical instruments and processes, have revolutionized the observatory. From a simple observing station it has been transformed into a great physical laboratory, where images of the sun and stars are studied with many powerful instruments, and celestial phenomena are experimentally imitated with the aid of electric furnaces and other sources of intense heat. The result has been a great gain in our knowledge of the origin, development, and decay of stars. This books explains in a popular way how the life histories of the sun and stars are investigated. One hundred and four half-tone plates, made from the best astronomical negatives, place before the reader the most recent results of celestial photography in most of its phases. 250 pages, 104 plates, 8vo, cloth; net $4.00, postpaid $4.27 Address Dept. 38 THE UNIVERSITY OF CHICAGO PRESS CHICAGO NEW YORK Published in Europe by William Wesley and Son, 28 Essex Street, Strand, London, Price, 16s. 6d. ESSAYS PHILOSOPHICAL AND PSYCHOLOGICAL. IN HONOR OF WILLIAM JAMES, PROFESSOR IN HARVARD UNIVERSITY This volume is intended to mark in some degree its authors' sense of Professor James's memorable services in philosophy and psychology, the vitality he has added to those studies, and the encouragement that has flowed from him to colleagues without number. From Prefatory Note. The New Realism..... Does Reality possess Practical Character? A Factor in the Genesis of Idealism.. Consciousness a Form of Energy. Perception and Epistemology.. World-Pictures... Naïve Realism: What Is It?.. Kant and the English Platonists. A Critique of Kant's Ethics The Abuse of Abstraction in Ethics PHILOSOPHICAL ESSAYS. Purposive Consistency, the Outline of a Classification of Values... Pragmatism in Esthetics. The Consciousness of Relation The Validity of Judgments of Character. PSYCHOLOGICAL ESSAYS. .GEORGE STUART FULLERTON .HERBERT GARDINER LORD ...KATE GORDON ..R. S. WOODWORTH .FREDERIC LYMAN WELLS NAOMI NORSWORTHY .JAMES MCKEEN CATTELL EDWARD L. THORNDIKE On the Variability of Individual Judgment. Reactions and Perceptions.... A Pragmatic Substitute for Free Will LONGMANS, GREEN & COMPANY. 91 Fifth Avenue, New York City A Monthly Journal, established in 1867, Devoted to the Advancement of the Biological Sciences with Special Reference to the Factors of Organic Evolution and Heredity CONTENTS OF MARCH NUMBER Invitation Papers at the Baltimore Meeting of the Botan- Darwin's Influence upon Plant Geography and Ecol- An Examination of Darwin's "Origin of Species" in the The Distinction between Development and Heredity in Inbreeding. Dr. EDWARD M. EAST. Breeding Experiments with Rats. Professor T. H. MORGAN. CONTENTS OF THE APRIL NUMBER Heredity of Hair Color in Man. GERTRUDE C. DAVENPORT and CHARLES C. DAVENPORT. A Mechanism for Organic Correlation, Professor G. H. The Progress of Plant Anatomy During the Last Notes and Literature: Heredity-The Nature of "Unit" Characters, DR. W. J. SPILLMAN. EnvironmentDR. FRANK E. LUTZ. Experimental Zoology-Hybridology and Gynandromorphism, Professor T. H. MORGAN. Echinodermata-Red Sea Crinoids, DR. AUSTIN HOBART CLARK. CONTENTS OF THE MAY NUMBER The Categories of Variation. Professor S. J. HOLMES. The General Entomological Ecology of the Indian Corn Plant. S. A. FORBES. Notes and Literature: Biometrics-Some Recent Studies on Growth. DR. RAYMOND PEARL. Experimental Zoology-Cuénot on the Honey Bee, Professor T. H. MORGAN. The Upholding of Darwin-Poulton and Plate on Evolution, V. L. K. CONTENTS OF THE JUNE NUMBER Heredity and Variation in the Simplest Organisms. Professor H. S. JENNINGS. The Color Sense of the Honey Bee Is Conspicuousness an Advantage to Flowers? JOHN H. LOVELL Variation in the Number of Seeds per Pod in the Broom, Cytisus scoparius. Doctor J. ARTHUR HARRIS. Present Problems in Plant Ecology: The Trend of Ecological Philosophy. Professor The Present Problems of Physiological Plant Notes and Literature: Notes on Evolution, V. L. K. The NATURALIST will be sent to new subscribers for four months for One Dollar THE SCIENCE PRESS Garrison, N. Y. Sub-Station 84: NEW YORK Lancaster, Pa. THE AMERICAN NATURALIST A MONTHLY JOURNAL Devoted to the Advancement of the Biological Sciences with CONTENTS Page I. The Non-muscular Articulations of Crinoids. AUSTIN HOBART CLARK. II. On Some Dinichthyid Armor Plates from the Marcellus Shale. BURNETT SMITH. 588 . 598 III. Are Species Realities or Concepts only. Professor J. H. POWERS. 611 V. Notes and Literature: Comparative Psychology - Bohn's "The Birth of Intelligence": Professor H. S. JENNINGS. Mammalogy-Osgood's Revision of the Mice of the Genus Peromyscus, Dr. J. A. ALLEN. Leo Errara, Professor CHARLES E. BESSEY. . 619 THE SCIENCE PRESS LANCASTER, PA. GARRISON, N. Y. NEW YORK: SUB-STATION 84 |