peridotites, occur in small lenticular masses or in narrow strips, which are always enveloped in a sheet of schistose talc or chlorite, and thus are never in direct contact with the gneisses through which they are believed to cut. They are classed as peridotites, pyroxenites and amphibolites, the former being the most common. The peridotites present several types in each occurrence, all merging into one another and forming a single geological unit. The principal types of the peridotites are dunite, harzburgite, amphibole-picrite and forellenstein. All are massive, as a rule, though exceptions are noted. The dunite is composed of olivine grains, octahedrons and rounded grains of picotite and chromite, plates of enstatite, prisms of light green hornblende and various alteration products of these, the most common being serpentine tremolite and chlorite. The Harzburgite and the other peridotites present no unusual features. They appear to be transition phases between the dunite and the various pyroxenites among which are recognized two types, an enstatite rock and websterite. The enstatite rock is made up almost exclusively of enstatite or bronzite and its alteration product talc. An analysis of the enstatite gave: SiO, Al,O, FeO CaO MgO MnO H2O Total The amphibolites are composed chiefly of amphibole. The most important type is composed of grass-green hornblende, anorthite and more or less corundum. The rock is fine grained and it is usually gneissic, although occasionally massive. Transitions through forellenstein into dunite were observed, although the distribution of the rock suggests its occurrence in a system of dykes cutting the latter rock. The hornblende has the following composition: SiO, Al,O, Cr2O, FeO NiO MgO CaO NaO K2O H2O Total 45.14 17.59 .79 3.45 .21 16.69 12.51 2.25 .36 1.34 100.33 Genth called the mineral smaragdite. Dana regards it as edenite. In addition to the rocks mentioned above, there are also present in the region massive serpenite, which was unquestionably derived from dunite, talc-schists, and soapstones derived from enstatite rocks and chlorite schists. In a second paper' the same author gives his reasons for considering these rocks as eruptive in origin. Shales and Slates from Wales.--Hutchins continues his studies of clays, shales and slates by an investigation of the nature of * Elisha Mitchell Sci. Soc. Jour., Pt. II, 1895, p. 24. 5 Geol. Mag., Vol. III, 1896, p. shales taken from some of the deepest coal mines in Wales. The chemical composition of the particular shale analyzed does not differ materially from that of some of the carboniferous shales from other coal fields. Physically the deeper shales are not much more compact than hard clays. The author reviews the results of his observations on shales and slates. He states that what takes place in a rock during its progress from clay to shale, is the development and crystallization of muscovitic mica and the production of chlorite. He also calls attention to the fact that dynamic metamorphism is made to explain many phenomena connected with the crystallization of slates, that are capable of being explained better by static metamorphism. The spots of many contact rocks are now thought to be secretions from a mineralizing solution, depositing in these spherical forms material collected from the rock body. By crystallization the spots pass over into cor. dierite, biotite or staurolite crystals. Notes.-Cushing declares that in addition to the rocks described by Kemp from the eastern Adirondacks there is a system of diabase dykes, which are older than the monchiquites and camptonites of the district. By melting certain rock powders in the presence of reagents Schmutz' has obtained aggregates of minerals which in most cases are very different from those composing the original rocks. Eklogite fused in the presence of calcium and sodium fluride yielded a mass of meionite, plagioclase and glass; leucitite with calcium chloride gave a mass composed of a glassy groundmass and plagioclase; with the addition of sodium fluride and potassium silico-fluride it yielded scapolite, mica, magnetite; with sodium chloride it produced augite, scapolite and magnetite and a glass matrix. Granite fused with magnesium and calcium chlorides and sodium fluoride gave andesine and olivine in a groundmass containing augite. Other rocks treated with other reagents gave analagous results. As the result of a series of experiments made with the view of discovering a medium with a very high specific gravity that will not attack sulphides, Retgers finds that the acetate and the mixed nitrate and acetate of thallium are both neutral toward sulphides. The former is available for separating minerals with a density below 3.9, and the latter those with a density below 4.5. 6 Trans. N. Y. Acad. Sci., XV, 1896, p. 249. 7 Neues Jahrb. f. Min., etc., 1896, I, p. 211. 8 Neues Jahrb. f. Min., etc., 1896, I, p. 213. In an article in the Neues Jahrbuch Bauer gives a German transscription of his article on the rocks associated with the jadeite of Turmaw, Burmah. Schroeder vander Kolk" describes briefly a series of rocks collected by Martin in the Moluccas. In the southern part of Amboina the rocks are mainly granite and peridotite, while in the larger northern part they consist of modern volcanics, as they do also on the other islands studied. These rocks are principally dacites and liparites, but on one island andesites occur. Both the dacites and the granite contain cordierite. The dacites are pyroxene and biotite varieties. The andesites are pyroxenic; mica schists, breccias and limestones occur also on the islands. The residue left after treatment of the limestone with acid contains quartz, sanidine, plagioclase, biotite, amphibole, orthorhombic pyroxene, hematite, garnet, cordierite, sillimanite and pleonost. BOTANY.1 The Evolution of a Botanical Journal.-In November of the present year the Botanical Gazette reaches its majority, by attaining the age of twenty-one years. It first appeared in November, 1875 under the name of the Botanical Bulletin, and consisted of four pages of short notes. It was edited by John M. Coulter, then professor of Natural Sciences in Hanover College (Hanover, Indiana). In his introductory note the editor stated that the object of the new journal was "to afford a convenient and rapid means of communication among botanists. The context shows that it was started as a distinctly western journal, intended to supplement the work of eastern botanical publications. The first volume included notes by the editor, and Thomas C. Porter, Samuel Lockwood, G. C. Broadhead, M. S. Coulter, Mary E. Pulsifer Ames, J. T. Rothrock, H. C. Beardslee, Coe F. Austin, George Vasey, Alphonso Wood, Isaac Martindale, Elihu Hall, E. A. Rau, and others who have long since diappeared from the botanical field. With the 9 Neues Jahrb. f. Min., etc., 1866, I, p. 19. 19 Cf. AMERICAN NATURALIST, June, 1896, p. 478. 11 Ib., 1896, I, p. 152. 1 Edited by Prof. C. E. Bessey, University of Nebraska, Lincoln, Nebraska, 2 Read before the Botanical Seminar of the University of Nebraska. 10, 1896. October opening of the second volume its name was changed to the Botanical Gazette, and the name of M. S. Coulter was added as joint editor. In 1883 by a reorganization of the management, John M. Coulter, Charles R. Barnes and J. C. Arthur became editors, an arrangement which proved to be so satisfactory to the botanists of the country as to become permanent. The next few years were trying ones for the ambitious editors, but the impetus given to botanical thought by the incoming of modern methods in teaching and study, and perhaps, also, by the organization of the Botanical Club of the American Association for the Advancement of Science, proved helpful in many ways. The Philadelphia (1884) and Ann Arbor (1885) meetings of the Botanical Club created much botanical enthusiasm, the results of which accrued to the benefit of the Gazette. The beginning of its second decade saw it much enlarged, improved in typography and apparently well established in the confidence of American botanists. Year by year it was still further increased in size, better paper was used, and the quality of the matter steadily improved. From the fifty-two pages of short, and mostly local, notes of volume I, we turn to the five hundred and sixty eight pages of structural, physiological, ecological, systematic and palæontological matter in volume XX. With the opening of the twenty-first volume an additional enlargement was found to be necessary, the numbers averaging sixty-five pages each. In the earlier volumes there were no plates, the first one occurring in volume VI, illustrating an article by J. C. Arthur on the trichomes of Echinocystis lobata. In the twentieth volume there were thirty-seven plates, while for the first half of 1896 the number was twenty-nine. The last stage in the evolution of this important factor in American botany was reached a few months ago when its financial management was transferred to the University of Chicago. It thus happily becomes an endowed institution, and the editors, relieved from all anxiety as to its business management, are free to develop it along strictly scientific lines. To the three editors whose efforts have given it the foremost place place among botanical journals are hereafter to be added several "associate editors"; at present these are G. F. Atkinson, V. M. Spalding, Roland Thaxter and William Trelease. Under the new regime it promises to be more cosmopolitan than before, and accordingly we are assured that the names of one or more European botanists will soon be added to the corps of editors. This factor in botanical science has thus been a growth, and it represents to-day much more than so many pages of printed matter. It has grown and developed as the science of botany has grown and developed in this country. When we look over the earlier volumes with surprise at the little notes which fill the pages, we must not forget that American botany had not then generally risen above such contributions. It is true that we had a few masters in the science, with Dr. Gray still in his prime, but these masters wrote little for general reading, and their technically systematic contributions were mostly published in the proceedings of learned societies. The one thing which stands out to-day in sharp contrast with the botany of two decades ago is the very great increase in the number of masters in the science who are making liberal contributions from many different departments. The many-paged Gazette of to-day, with its rich variety of matter, differs no more from the four-page Bulletin of 1876 than does the botany of the two periods.-CHARLES E. BESSEY. The North American Species of Physalis and Related Genera.—In a recent number of the Memoirs of the Torrey Botanical Club (Vol. IV, No. 5) Mr. P. A. Rydberg publishes an important contribution to our knowledge of our species of Physalis and related genera. Every one who has attempted to accurately identify any of the native species of Physalis knows well how difficult and discouraging the task has been. Commenting on this Mr. Rydberg says: "The reason is not that the descriptions are so badly drawn, but that only about one half of the actual number of species have, as a rule, been recognized." After a critical discussion covering fifteen pages the author characterizes the six genera which he includes in his monograph. These are Margaranthus, with four southwestern species; Physalis, with thirty-nine species; Quincula, with one Rocky Mountain species; Leucophysalis, with one species of the northern United States and Canada; Chamasaracha, with four species of the southwestern United States; Oryctes, with one species from Nevada. Throughout the paper the nomenclature and synonymy receive full attention, the citations being unusually complete. The descriptions are concise, and apparently drawn with great care. And last, but by no means least, there is a full index of species and synonyms given at the end of the monograph. Altogether it is an unusually good piece of work.-CHARLES E. BESSEY. Professor Prentiss.-The recent death (August 14th) of Professor Albert Nelson Prentiss of Cornell University calls for more than a mere |