any importance only one page is shown in facsimile in the present edition. The rest of the text is reproduced on the left hand pages while the translation appears on the following pages. The last six pages are devoted to algebra, chiefly relating to quadratic equations, and, in closing, the author states that he "wished to set down the things which are necessary and familiar in this kingdom." The formula near the bottom of page 37 is not clearly stated. Professor Smith's name is a sufficient guarantee that the work is in an attractive form.

UNIVERSITY OF ILLINOIS

G. A. MILLER

Introduction à l'étude pétrographique des roches sédimentaires. Par M. LUCIEN CAYEUX. Mémoires pour servir à l'explication de la carte géologique détaillée de la France. Paris: Imprimerie Nationale 1916. Quarto, 1 vol. text, pp. viii+ 524, 80 figures; 1 vol. LVI plates.

It is a curious fact that although Sorby, the father of modern petrography, was espe'cially interested in sedimentary rocks, those who followed him, with the exception of a small but persistent succession of workers in his own country, almost abandoned them in favor of the igneous rocks. The author of the book under review has elsewhere suggested that this was perhaps due to the lure of greater mystery in the igneous rocks and to the lack of knowledge, before the Challenger expedition, about the sediments of today. The reviewer has always been inclined to attribute the preference for the study of igneous rocks to their greater and more obvious diversity, which made it easier to find something new in them and gave them a greater esthetic attractiveness. Whatever the cause the present work will be the most powerful influence that has yet been brought to bear in changing that tendency. Indeed, in French-speaking countries Cayeux's influence is already very manifest. If the beauty of the sedimentary rocks has been considered inferior the enthusiasm of the author will surely correct that impression.

66

The work marks an epoch in its field and is written with a breadth of view worthy of the fundamental importance of the sedimentary rocks in the interpretation of the history of the earth. The author not only stands alone in the extent and thoroughness of his monographic investigations in this field, but as the successor of Élie de Beaumont, Fouqué and Michel-Lévy at the Collège de France he is, so far as the reviewer knows, the only person occupying a chair devoted entirely to the teaching of the petrology of sedimentary. rocks. On his inauguration the name of the chair he occupies was changed from "Chair of the Natural History of Inorganic Bodies," to Chair of Geology," but it might well have retained its old name, for as he says in his inaugural address, "The science of the sedimentary rocks is and will remain for us a natural history of the ancient and modern sediments." It is the treatment from this point of view and the enthusiasm and wide personal experience which the author brings to it that gives to a book which one might expect to find dry and technical a freshness, interest, and charm that make it fascinating reading. Furthermore, the book is so full of original observations drawn from the writer's many years of study that no student of sedimentary rocks, be he petrographer or merely stratigrapher, can afford to leave it unread.

The work is divided into two parts. The first deals with methods of analysis of sedimentary rocks, the second with the diagnostic characters of the constituents, which fall into two groups-the minerals and the remains of organisms.

The first part is refreshingly free from pedantry or love of technique as an end in itself, though the artist's pleasure in some refined and delicate method often finds expression. Methods of handling rocks of different types according to their induration or susceptibility to attack by acid are discussed, but the possible complexity of the procedure appropriate to any individual rock and the need of adapting the methods used to the particular rock and to the object of the investigation are pointed out. Quantita

tive results are sought, but the difficulties of obtaining them are recognized and the usefulness of quantitatively expressed results that may not be accurate in themselves but still may permit of valuable comparison with one another, is admitted. The reader feels throughout no impulse on the part of, the author to fix standards but merely that desire to give help, out of his own rich but painfully accumulated experience, which led him to prepare the book. Any one who comes to this book for a rigorous method that will enable him to turn out orthodox studies of sedimentary rocks will be disappointed, but those who want to help in advancing the borders of knowledge about this subject will find guidance and inspiration. The methods of analysis are grouped under three headsphysical, microchemical and chromatic. The physical analysis includes different processes sometimes grouped in this country under mechanical analysis, and the preparation of thin sections which in dealing with weakly bound sedimentary rocks often calls for special methods. The demonstration of the ease of application and delicacy of microchemical analyses is one of the outstanding features of the book. Under chromatic analysis the author discusses various methods of staining. In the discussion of all these methods he selects, weighs, evaluates and contributes on the basis of his own experience, without attempting any formal completeness..

Perhap Cayeux's greatest achievement is the interest he is able to give to his discussion of the minerals of sedimentary rocks, of which of course he considers only the more common, both essential and accessory. It is in this part of the book that his treatment of the subject as natural history is illustrated in the most novel and interesting way. The individual mineral is to the author a record of environments-of the environment in which it originated and of those through which it subsequently passed-and it therefore contributes to the reconstruction of the history and geography of the past.

The last part of the book deals with the remains of organisms as constituents of the

rocks. Needless to say, specific determinations of organisms are not the purpose of a treatise on petrography. But here, too, the problem of past environment as recorded by the remains, both as remnants of once living organisms and as mineral substances, is the object of study. This part therefore deserves the attention of paleontologists as well as of petrographers and stratigraphers.

Vivified throughout by the author's own experience the work must lack that perfect completeness that would assure it against being found defective in the treatment of some special topics or methods that may be in favor with individual readers. But every reader will surely be glad to accept these omissions for the sake of the vigor and readibility that go with them. American petrographers, for instance, will be struck by the absence of any discussion of the use of liquids of known indices of refraction in the determination of minerals. But as compensation they may profit by adopting some of the elegant microchemical tests described, which have the advantage that they can often be applied directly to the thin section and do not require the disintegration of the rock. Likewise the suggestions given on pages 305 to 309 for the determination of minerals by their general appearance may be a valuable antidote to the habit into which the devotee of "index liquids" is likely to fall, of resorting to his liquids in blind routine, just as the man with the slide rule habit gets out his machine to find the product of 2 X 2.

The physical quality of the book is worthy of its subject matter, and it is a fact for contemplation and an honor to the fine French scientific spirit, exemplified by the entire work, that it bears the date 1916.

MARCUS I. GOLDMAN

U. S. GEOLOGICAL SURVEY

SPECIAL ARTICLES NOTES ON THE OCCURRENCE OF GAMMERUS LIMNAEUS SMITH IN A SALINE HABITAT

THE capacities of various organisms for withstanding relatively wide ranges of environmental conditions has received considerable

attention at the hands of physiologists and students of animal behavior, and is a problem which must ultimately be considered in greater detail by ecologists, students of geographic distribution and organic evolution.

The purpose of this note is merely to call attention to the occurrence of Gammerus limnaeus Smith, normally a fresh water2 species, in in a peculiar and rather saline habitat.3

In the summer of 1920 the writers visited the Ice Spring Craters lava field of the Sevier Desert in the ancient Lake Bonneville basin described in detail by Gilbert. On climbing down into the old lava vent of the Terrace crater we were surprised to find a small crustacean abundant in the small pool of

We are indebted to Mr. Waldo L. Schmitt, associate curator of marine invertebrates in the U. S. National Museum, for the determination of the species. The specimens are in the National Mu

seum.

2 The key to the taxonomic and distributional literature is furnished by Weckel's paper on the fresh water Amphiopoda of North America (Proc. U. S. Nat. Mus., 32: 42-44, 1907), and individual citations need not be given here. The species was first dredged in Lake Superior. It has been taken near Long's Peak, Colorado, at an elevation of 9,000 feet; from a cool spring, Fire Hole Basin; from Shoshone Falls, Idaho; Flathead Lake, Montana; and from the Yellowstone National Park. It is reported from Fort Wingate, N. M., and from the Wasatch Mountains and Salt Lake City, Utah. It is impossible to determine from the records whether all the localities were fresh water habitats, but that it is typically a fresh water form can admit of no possible doubt. It has been taken from the stomachs of trout from brooks near Marquette, Mich.

3 The genus Gammerus has species which occur in more or less saline coastal habitats and in non

clear water at the bottom. It was noted that a number of the animals were very slightly pigmented, apparently indicating that in the semi-darkness of the pool they were approaching cave conditions. In all instances, however, the eyes were fully pigmented. The presence of the Gammerus led to the assumption that the water was non-saline and we were preparing to replenish our water bag when taste showed it to be distinctly brackish.

A sample of the water was therefore taken in a clean Mason fruit jar from which it was afterwards transferred to citrate bottles for shipment to the laboratory. The water had a freezing point lowering of 0.410° C., indicating an osmotic concentration of 4.94 atmospheres and an electrical conductivity of .0138 reciprocal ohm. The hydrogen ion concentration of the water (determined electrometrically) was CH 0.409 X 10-7 pH7.388. Analysis showed the following composition.

Total

6 There was apparently considerable organic matter in solution. This could easily be derived from bat guano which was observed on the lava ledges surrounding the pool.

7 Carbonates and bicarbonates were determined by the titrametric method proposed by Scales (SCIENCE, N. S., 51, p. 214, 1920).

8 Calculated from bicarbonate data according to the formula 2RHCO, + heat= · R2CO2+CO2 + H2O.

The Terrace crater, and indeed all of the craters of the Ice Spring Craters group, is unquestionably post-Bonneville in origin. There is no trace of wave work on the outer slopes of the craters such as are so conspicuous on Pavant Butte to the north, and neither lacustrine sediments nor evidences of subaqueous erosion appear on the surface of the evidently recent lava fields as they do on the Fumarole Butte lava field to the northwest.

The depth of the vent of the Terrace crater is 260 feet below its general rim and 220 feet below the sill of the last outflow. The problem of the original introduction of Gammerus into the small pool of water occupying the bottom of this crater is that of the transportation of small crustacean species or their eggs in general. The point of physiological interest is the occurrence of this species, hitherto reported from non-saline waters, in water of this concentration.

Ross AIKEN GORTNER, Division of Agricultural Biochemistry, University of Minnesota,

J. ARTHUR HARRIS, Station for Experimental Evolution, Carnegie Institution of Washington

9 An average value based on NaCl contents of 4.8790 gr. calculated from residual Na and 4.7870 calculated from residual Cl. The difference of 0.092 gram per liter is within experimental error when one remembers that the above calculations are purely empirical and also when one considers that in some instances the actual analytical values, and consequently accompanying experimental errors, were multiplied by 50 to bring the calculation to a liter basis.

THE POSSIBLE ORIGIN OF EYELESS CAVE

ANIMALS

DURING the past nine years vast numbers of Cladocera of several species have been reared in the writer's laboratory. For one purpose or another many thousands of these have been examined with the microscope. About a year ago was found the only marked aberration of the eye structure which has been noted. This was a Simocephalus without any trace of an

eye.

disUnfortunately this individual was covered among the small number just killed for use in making some permanent slide mounts. The killing of this individual was unfortunate in that a Cladoceran when killed becomes somewhat opaque while the live animal is so transparent that internal structures can be clearly distinguished. Nor was the differentiation so good in the completed mount as in a live animal. It was clear however both in the freshly killed specimen and in the mount that not only the eye pigment but the entire eye structure was lacking. The ocellus was present and normally pigmented. While it is not quite demonstrated in the mounted specimen it is probable that the optic ganglion is normally developed in the eyeless individual.

It is a source of keen regret to the writer that this eyeless individual was not discovered alive so that offspring could have been obtained from it and light thrown on the nature of the peculiarity, whether of genetic consequence or merely an accident in development. No eyeless individuals were found among sibs and many offspring of sibs of this eyeless individual. This fact however does not convince one that eyelessness in this case may not have been inheritable, since in these prevailing parthenogenetic forms there is no chromatic reduction in the maturation of the egg and hence no segregation of characters is expected. If the eyeless condition of this individual were due to a mutation its descendants should have been eyeless, but un

less the mutation occurred in a cell generation earlier than that in which the egg itself was differentiated no other germ cells of the parent or collaterals of the eyeless individual should bear the factor for eyelessness.

Observation of the occurrence of an eyeless mutant and the transmission of this characteristic would be of great interest as bearing upon the probable origin of eyeless cave animals. As is well known, many cave animals, particularly crustaceans, are without eyes or have extremely degenerate eyes.

It has been suggested that such cave forms may have arisen by "orthogenesis" (many small mutations) or, by implication, possibly by a single large mutation.1

Eyelessness in these forms is associated with lack of body pigment. Pigmentless animals, such as cave amphipods for example, may suffer deleterious effects if they come under the influence of the actinic rays of sunlight. Such animals are conspicuous and an easy prey to their natural enemies. In so far as a general vision may aid such organisms in reaching a suitable locality for securing food eyeless individuals are at a disadvantage in the open in competition with eyed individuals. On the other hand in caves and similar situations they are shielded from light, are not rendered conspicuous by their whiteness and are at no disadvantage in competition for food. It would seem that they have become segregated in caves and other retired situations because they can survive there and are unable to do so elsewhere. The occurrence in Drosophila of a "bareyed" mutant (eye much reduced in size and in effective elements) and an "eyeless " mutant (in most cases not really eyeless but eyes more or less rudimentary) lends credence to the theory that eyeless cave animals, or such animals with very defective eyes, may have arisen as the result of mutations. One does not however lose sight of the fact that the eyeless daphnid mentioned may have arisen from a disturbance in development such as the writer has seen in eyeless sala1 Banta, Carnegie Institution of Washington, Publication No. 67, 1907.

It was voted at this meeting that the Christmas meeting of the Chicago Section be held in Toronto, in affiliation with the Convocation week meetings of the American Association for the Advancement of Science.

A dinner at which forty-seven persons were present was held at the Quadrangle Club on Friday evening.

At the sessions of Friday and Saturday forenoons, the following papers were presented: 1. I. J. Schwatt, "On the expansion of powers of trigonometric functions."

2. I. J. Schwatt, "On the summation of a trigonometric power series.''

3. W. B. Ford, "A disputed point regarding the nature of the continuum."

4. Mayme I. Logsdon, "The equivalence of pairs of hermitian forms."

5. C. C. MacDuffee, "Invariants and vector covariants of linear algebras without the associative law."

6. E. J. Wilczynski, "Some projective generalizations of geodesics.''

7. W. L. Hart, "Summable infinite determi

nants."