of $25,000 a year for a period of twenty-five years from Sir John and Lady Eaton. This is to provide for a full-time clinician in the department of medicine and a half-time clinician in pediatrics.

THE Court of governors of the University College of North Wales, at their meeting at Bangor, appointed a deputation to wait upon the Board of Agriculture regarding the proposal to have only two schools of forestry in Great Britain-one in Scotland and the other either at Oxford or Cambridge. Fears were expressed that if this was carried into effect it would mean the extinction of the forestry department in connection with the University College of North Wales. It was felt that one of the two new schools should be established in Wales, with its large area of forests.

SIR ARTHUR NEWSHOLME, K.C.B., who is now in the United States has accepted for the

drawing and descriptive geometry; L. A. Hamilton, analytical chemistry; H. B. Luther, civil engineering; C. S. Robinson, industrial chemistry; R. H. Smith, mechanical engineering; C. E. Turner, biology and public health.

MR. WILLIAM MORRIS JONES, M.Sc., B.A., has been appointed lecturer and experimentalist in physics at the University College, Bangor.

DISCUSSION AND CORRESPONDENCE QUANTITATIVE CHARACTER-MEASUREMENTS IN COLOR CROSSES

THE writer, although working in plant and not in animal breeding, has been struck with the desirability of finding a more exact quantitative measure of degree of distribution of coat color in animal crosses. The following is suggested. Photograph the animal in a centered position on its two flanks. On the

in the new school of public health of the Johns Hopkins Medical School.

CHARLES JOSEPH TILDEN, professor of civil engineering at Johns Hopkins University, has been elected professor of engineering mechanics in Yale University and assigned to the Sheffield Scientific School.

AUSTIN F. ROGERS and Cyrus F. Tolman, Jr., of the department of geology at Stanford University, have been promoted from associate professors to professors.

MORRIS M. LEIGHTON, Ph.D., Chicago, 1916, has accepted a joint-position as assistant professor of geology at the University of Illinois and as Geologist on the Illinois Geological Survey.

AT the Massachusetts Institute of Technology the following assistant professors have been promoted to associate professorships: H. C. Bradley, department of drawing and descriptive geometry; C. E. Locke, department of mining engineering and metallurgy, and N. C. Page, department of electrical engineering. The following instructors have been appointed assistant professors: J. B. Babcock, 3d, railroad engineering; S. A. Breed, mechanical

determine the area of the color markings under investigation with a planimeter. These areas, reduced to percentages of the entire area photographed, will give a quantitative expression for the degree of extension of the character markings. The writer would venture to suggest the following possibility in the study of the operation of an extension factor. Let the photographic prints be ruled off in square centimeter areas with India ink. Then the relation of the color areas to the region of the animal's anatomy can be definitely established upon a quantitative basis. This having been done for the parents, the operation of an extension factor could be studied both quantitatively with respect to the amount of surface over which the factor became operative, and topographically with respect to the location and range of its operation in the progeny. If desired, it would be a comparatively simple matter to construct a cross-wire screen behind which the animal could be photographed, and which would thus reproduce the areas to scale directly.

In the study of inheritance in plants, the application of this method suggests itself very readily in color-inheritance in the seed-coats of beans and other legumes. By photograph

ing the seeds with a photomicrographic apparatus, enlarging them a sufficient number of times, it is easy to bring the markings within the range of size where the use of the planimeter becomes a practical matter.

H. F. ROBERTS KANSAS STATE AGRICULTURAL COLLEGE, April 28

SURPLUS BISON FOR MUSEUMS

THERE is now a great surplus of male bison in the main Canadian herd at Buffalo Park, Wainright, Alberta. This is the largest herd of bison in the world, numbering 3,561 and is maintained by the Canadian government under the administration of the Dominion Parks Branch of the Department of the Interior.

Besides these 3,561 bison, there are also 8 at the Rocky Mountains Park, Banff, Alberta, and 182 at Elk Island Park, Lamont, Alberta. In 1909, there was a total of 685 bison at Buffalo Park, 118 were imported during 1910, 1911 and 1912 from the Pablo herd in Montana, and 10 bison cows from the Rocky Mountains Park during the winter of 1913–14. With the exception of these the increase has been due to natural causes.

It is said that elsewhere the percentage of male to female calves has been higher among bison in semi-captivity within enclosed parks than was the case when the herds freely roamed the plains. This has proved to be the case in the main Canadian herd, so that there is a great surplus of male bison that are not needed for herd purposes.

It is proposed to dispose of these surplus male bison for the nominal sum of $250 each to bonafide natural history museums of Canada and the United States, and further information can be obtained by such museums from Mr. J. B. Harkin, Commissioner of Dominion Parks, Department of the Interior, Ottawa, Ontario, Canada.

This should prove a splendid opportunity not only to secure skins for mounted specimens and groups, but also for museums to send their preparators to Buffalo Park to secure photographs, color sketches and acces

sories for habitat groups, and to secure skeletons, anatomical preparations of internal organs and parasites.

HARLAN I. SMITH

MUSEUM OF THE GEOLOGICAL SURVEY,

OTTAWA, CANADA

INFORMATION SERVICE FOR EXPERIMENTAL BIOLOGISTS

TO THE EDITOR OF SCIENCE: The Federation of American Societies for Experimental Biology, comprising the sciences of physiology, biological chemistry, pharmacology and experimental pathology, is now organizing an information service to serve as a medium of communication between persons seeking positions for teaching or research and institutions that wish to fill vacancies in these sciences. Persons, whether members of the federation or not, and institutions desiring to avail themselves of the service may communicate with Professor Edgar D. Brown, secretary of the executive committee of the federation, University of Minnesota, Minneapolis, Minn., and such information as is available will be supplied without cost to the applicant. Applicants are requested to supply the service with ten copies of their application, which should cover the following points:

1. For the Person seeking a Position: age; college and university training; degrees received; academic or other positions held; list of scientific papers published; membership in scientific societies; position and salary desired; copies of letters of recommendation; names and addresses of persons who can supply further information regarding the applicant; and any other information that the applicant desires to submit.

2. For the Institution desiring to fill a Vacancy: title of vacant position; date to be filled; requirements as to teaching or other routine work and research; salary to be paid; prospects of tenure of office and advancement; and any other information that the institution desires to submit.

The service does not undertake to recommend or to pass judgment upon applicants. It aims merely to serve as a clearing-house for such information as the above and to

The Mineral Deposits of South America. By BENJAMIN L. MILLER, professor of geology, Lehigh University, and JOSEPH T. SINGEWALD, associate professor of economic geology, Johns Hopkins University. New York, McGraw-Hill Book Company, Inc. 1919. Pp. 598, with 61 figs.

South America is a continent richly endowed with mineral resources: In Brazil are the largest high-grade iron-ore deposits in the world; at Chuquicamata, Chile, is the largest copper deposit in the world and the copper resources of Chile are second only to those of the United States; the nitrates of Chile constitute a world monopoly of that commodity; the tin lodes of Bolivia are by far the most productive in the world, their annual output being seven fold that of their nearest competitor; the world's greatest vanadium deposits are in Peru; and the only considerable source of platinum outside of Russia is in Colombia. The mineral deposits are not only of great importance commercially but are also of deep interest scientifically; and, as the present book by Professors Miller and Singewald shows, not more than a beginning has been made in solving the geologic problems they present.

The book under review, as we are told in the preface, is "the outcome of an extended trip through South America made by the authors in 1915." It is essentially a digest of available information on the mineral deposits of that continent, supplemented, however, by data the authors obtained during the visits, necessarily hasty, that they made to many of the mineral deposits of Brazil, Chile and Peru.

The opening chapter of the volume gives an outline of the geography, general geology and mineral resources of South America. It sketches also the history of the growth of the mineral industry, discusses the relation of mining to other industries, and outlines the probable trend of the future development.

In view of the ground covered, the chapter, comprising thirty-two pages, is somewhat scant. It could be improved also by the addition of a series of outline maps of the continent showing quantitatively where the more important mineral commodities are produced, and by the insertion of statistical tables and diagrams showing the relation of South America's mineral output to that of the rest of the world. Such aids in giving the reader generalized views of the continent as a whole are conspicuously few in the present volume, but their urgent desirability should be considered by the authors when a new edition is planned. In places throughout the book there is an unnecessarily abundant use of local Latin-American terms, for most of which the authors could easily have substituted perfectly good English equivalents.

The remaining eleven chapters take up in alphabetical order the countries of South America. The description of the mineral resources of each is introduced by a summary of production. In places some statistical errors have crept in, as on page 77, where the outputs of lead, zinc and tin of Bolivia are given in terms of metal, whereas the figures cited are in reality those of ore or concentrate. Nor is it mentioned that the unit employed is the metric ton. These oversights are pointed out in passing, because current international statistics of mineral output are commonly vitiated by similar lapses. The summary of mineral production is followed by sketches of the topographic and geologic features of the country, of the distribution of the mineral deposits, and of the occurrence of the chief mineral resources. This general treatment is followed by more detailed descriptions of the important deposits and districts. Each chapter closes with a selected bibliography, the number of entries ranging up to 225 titles for the chapter on Chile. The entries are generally accompanied by brief synoptic characterizations. It is not always indicated that some Latin-American entries are merely translations of papers that appeared originally in French, German, American or other publications.

One of the notable sections of the volume

is the account of the Bolivian tin veins. Professors Miller and Singewald were fortunate in finding fossil plants in the shales at Potosi, and as a result of this discovery were able to establish that the tin veins at Potosi were formed in Pliocene or Pleistocene time. This is a remarkable conclusion and shows that these wonderfully productive tin lodes are in a geological sense extremely youthful; in fact they are probably the most youthful economically valuable mineral deposits of first rank in the world. Professors Miller and Singewald extend this age determination to all the Bolivian tin veins and maintain that they are all of Pliocene age. This conclusion may or may not be true, for the veins of the different districts appear to be associated with igneous rocks of a wide range of texture: pegmatites, aplites, granite, granite porphyry, rhyolite porphyry, rhyolite and "true quartz porphyry." As a matter of fact, no thorough field study of the Bolivian tin veins as a whole has yet been made. The studies hitherto made have been mainly petrographic, by geologists who have not collected the specimens they studied. It is not to be expected that a very deep insight into the fundamental problems could be attained by that method. Even in such a relatively subordinate matter as the nomenclature of the igneous rocks the petrologist has felt it necessary to use such obsolescent, non-committal terms as quartz porphyry to describe some of the rocks to which certain Bolivian tin veins are genetically related. When field work becomes the main method of attack and the microscope is used as an auxiliary-a powerful auxiliary it is truemore satisfactory results will be attained, and it is therefore a pleasure to learn that Professor Singewald is returning to Bolivia in order to take up a careful study of the tin veins in their broader geologic aspects.

Another district of special interest is Corocoro in Bolivia, which like the Lake Superior district is one of the world's two productive copper districts in which the chief ore mineral is native copper. Brazil holds the distinction of having in the Morro Velho mine the deepest mine in the world, the lowest workings

having attained a vertical depth of 6,128 feet. The ore on the lower levels averages nearly $13 a ton in gold and indicates an extraordinarily long vertical range of gold-ore deposition. Apparently not much is known about the geology of this remarkable ore body, however. There are many other interesting deposits described in the book, but it would lengthen this review unduly even briefly to call individual attention to them. The outstanding feature of the economic geology of the South American continent is its preeminence in the number of its geologically youthful primary ore deposits of the first order of magnitude.

Professors Miller and Singewald have placed all interested in the mineral resources of South America under a deep debt for the labor they have expended in marshalling the widely scattered information and for presenting it attractively in a condensed and easily usable form. They can be gratefully assured that they have filled a genuine want in the literature of economic geology.

ADOLPH KNOPF

UNITED STATES GEOLOGICAL SURVEY

THE ECOLOGY OF NORTH AMERICAN LYMNEIDE

In a recent paper in SCIENCE1 the following statement appears: 66 There are three groups of limnæas found in North America, the abysmal limnæas including Lymnæa (Acella) haldemani Binney, the moss limnæas including Lymnaea (Galba) truncatula Müll., humilis Say, and the marsh limnæas including Lymnaea stagnalis, L. columella," etc. This classification of our pond snails is so unusual and so far from representing the true ecological relations of this group, as well as of the allied groups Planorbis and Physa, that a few observations on the subject seem necessary.

As far as known there are no abysmal lymnæas or other fresh-water pulmonates in America, comparable to the true abysmal fauna of the deep lakes in Switzerland, where Lymnaea stagnalis occurs in Lake Geneva at a depth of 250 meters and Lymnæa abyssicola 1 SCIENCE, N. S., XLVIII., p. 578, 1918.

in Lac Leman at depths of 25 to 250 meters.2 In the Swedish lake Vätter, mollusks, including lymnæas have been dredged from depths down to 120 meters. In America no such depths have yielded mollusks in our freshwater lakes, the deepest water from which lymnæas have been found being in Lake Michigan where several species were obtained at High Island Harbor at a depth of 10 meters.* It is possible that some of the deep western lakes, as Lake Pend d'Orielle, Idaho, examined by the writer some time ago, may contain a deep-water fauna.

The species cited as an example of abysmal lymnæas, Acella haldemani (Desh.) Binney, is really a shallow-water, swamp-loving species, when adult, in the fall, living at or near the surface attached to vegetation in water less than five feet deep. In summer (July) the young may be found in water not exceeding six feet deep, among such plants as Potamogeton."

The present center of distribution of American lymnæas is the Canadian faunal region, where upwards of 50 species and races live. North and south and east and west of this area there is a more or less rapid decrease in number of species. It is in this area that we find the greatest variation in the ecological relations of the group. This is due in part to the effect on the topography made by the great ice sheet which swept over the territory during the Pleistocene Period, and left upon its retreat the largest number of ponds and small lakes known in any part of the world. As typical pond and lake animals, the lymnæas have reacted favorably to this profusion of small bodies of water and a large and varied fauna has resulted. This is also true of other

2 Forel, Bull. Soc. Vaudoise des Sci. Nat., X., p. 217; XIII., p. 1 (1869, 1874).

3 Internationale Revue der gesamten Hydrobiologie und Hydrographie, Band 7, Heft 2-3, pp. 146-204, 1915.

4 Walker, Nautilus, IX., pp. 3-5, 1895.

5 For the life history and ecology of this species see Baker, Nautilus, XXX., pp. 135-138; Tech. Pub. No. 9, N. Y. State College of Forestry at Syracuse University, 1918.

groups of fresh-water mollusks especially the related fresh-water pulmonates, Planorbis and Physa. Ecologically, our lymnæid fauna may be divided into about five types:

1. The open shore lake type, where the environment is an open shore of a lake exposed to the full force of the winds and waves. Here such lymnæas as Lymnaea stagnalis lilliana Baker, Galba catascopium Say, G. emarginata Say, and G. nasoni Baker are common and typical of such a habitat.

2. The quiet bay or pond type, where the environment is protected from the force of the waves and wind by barriers of one kind or another. The water is shallow and there is usually an abundance of vegetation, such as Scirpus, Potamogeton, Castalia, Nymphæa, Typha and filamentous algae which provide much of the food of these snails. Such species as Acella haldemani (Desh.) Binn., Pseudosuccinea columella (Say), Bulimnea megasoma (Say), and Lymnæa stagnalis Linné are typical of such a habitat.

3. The marsh type, where the water is shallow, seldom more than three or four feet deep, and where there is an abundance of swamp vegetation such as Typha, Pontederia, Decodon and a few Nymphæa. The bottom is usually of mud of mud or accumulated vegetable débris. Such species as Galba palustris (Müll.), G. obrussa (Say), G. reflexa (Say), and G. elodes (Say) are characteristic of this kind of a habitat.

4. The mud-flat type. This type of habitat may border a swamp, pond or river, where the water is quiet and where an area of wet mud is left just above the water line. Here small species of the subgenus Simpsonia are at home and we find such species as Galba parva (Lea), G. dalli (Baker), G. G. umbilicata (Adams), and some of the small varieties of G. obrussa (Say) living by thousands, simulating the marine Littorinas in their ecological relations.

5. The intermittent pool or stream. This is a type of habitat found in all parts of the Baker, "Monograph Lymn. N. A.," pp. 52-67,

1911.