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$500 the first year, $750 the second year, and $1,000 the third year. Such fellows will spend half their time in the private clinic of Dr. Todd or Dr. Burch, and the other half in laboratory and clinical work and in pursuit of certain courses for specialists in ophthalmology and otolaryngology at the university. For work done in these private clinics, credit will be given toward the degree granted by the university in the course of ophthalmology and otolaryngology given at the University of Minnesota, to accepted doctors of medicine covering a period of three years which prepares the physician for the specialty of ophthalmology .and otolaryngology.

THE department of architecture of the University of Illinois is planning to take a leading part in rebuilding storm-stricken Mattoon. Sixteen architects of this department are to draw up sixteen standard plans for houses, the cost of which will range from $800 to $1,400. This work is being done in line with the school for city planning now being arranged for the coming summer. Officers of the university have expressed the hope that the institution may have an opportunity to duplicate on a larger scale in France what is now being done in the city of Mattoon.

PROFESSOR G. H. CLEVENGER, of Stanford University, has been appointed research professor in metallurgy and has been released from elementary and routine teaching.

PROFESSOR JOHN R. ALLEN, head of the department of mechanical engineering of the University of Michigan, has been offered the deanship of the college of engineering and architecture of the University of Minnesota.

MISS PAULINE H. DEDERER, instructor in zoology at Barnard College, has resigned to become assistant professor in biology at the Connecticut College for Women, New London.

DR. P. G. H. BOSWELL, lecturer in geology at the Imperial College of Science and Technology, London, has been appointed the first holder of the George Herdman chair of geology in the University of Liverpool. The establishment of a chair of geology in the university has been long delayed, and is now

possible owing to the generosity of Professor and Mrs. Herdman, who have endowed the chair as a memorial to their son, the late Lieutenant George Herdman.

DISCUSSION AND CORRESPONDENCE
THE PHYSIOGRAPHY OF THE LOWER AMAZON
VALLEY AS EVIDENCE BEARING ON
THE CORAL REEF PROBLEM

THE recent revival of the discussion of the origin of coral reefs1 has raised many questions which involve not only the coral islands, but also the displacements of the strand lines of the continents throughout the tropics, for the changes in level of the tropical seas invoked by Daly must have been recorded on the continents as well as on the islands. It seems, therefore, that a thorough investigation of at least a considerable number of critically situated continental strands of the tropics must be made before the evidence for or against the acceptance of the glacial control theory may be considered complete.

Recently, in his reading, the writer found an account of the physiography of the lower Amazon valley2 to which it seems worth while to call attention for the benefit of any who may undertake an investigation of the evidences of strand-line displacements in the tropics.

A brief abstract of a portion of Smith's paper follows: All of the larger rivers entering the lower Amazon from the south, and the Trombetas entering from the north, have lakelike expanses in their lower courses into which the Amazon, at times of flood, is pouring silt which is gradually filling them up. Meanwhile the upper ends of the estuaries are being filled by their own rivers. Some of the latter, which are muddier than others, have already trans

1 Daly, R. A., "The Glacial Control Theory of Coral Reefs," Proc. Am. Acad. of Arts and Sciences, Vol. 51, 1915, 157-251. Davis, W. M., "A Shaler Memorial Study of Coral Reefs," Am. Jour. Sci., 4th ser., Vol. 40, 1915, 223-271. Vaughan, T. Wayland, "The Platforms of Barrier Coral Reefs" (abs.), Am. Geog. Soc. Bull., Vol. 46, 1914, pp. 426-429.

2 Smith, H., "Physical Geography of the Amazon Valley," Am. Nat., Vol. XIX., 1885, 27-37.

formed their former estuaries into alluvial plains above which rise scattered rocky islands. This is particularly true of the northern tributaries of the lower Amazon, except the Trombetas, which has relatively clear water, and has not yet filled its estuary.

The author suggests that the physiographic features described above may be interpreted as the result of a moderate drowning of the region followed by the filling up of the estuary of the Amazon by the heavy silt burden borne by that river:

Gradually the alluvial land at the head of the bay extended eastward, filling up the estuary with islands. As this eastward movement went on, the branch estuaries were blocked up at their mouths by islands which formed in front of them. Where the branch received a muddy tributary it also filled up; but the clear water tributaries like the Tapajós, Xingú, and Trombetas, brought down no sediment, and their estuaries, closed at the mouths, assumed the form of lakes.

That the phenomena described are the result of changes in level and not merely of the ponding of the tributaries by sediment from the Amazon, is indicated, as the author points out, by the fact that the Tocantins River, which enters the sea directly, has a similar estuary.

The physiographic phenomena here described seem to point to a relatively recent period of lowered sea level (or land uplift) followed by a rise to the present position (or a sinking of the land). The phenomena may have been associated with the changes in sea level postulated by Daly, or they may be due to local crustal movements. Physiographic studies of a large number of tropical rivers would go far toward solving the problem.

UNIVERSITY OF ILLINOIS

QUOTATIONS

JOHN L. RICH

A PIONEER IN PHYSICS

FORTY-SEVEN years of collegiate teaching constitute in themselves a sufficient title to honor, even though their number be only a record of faithful and continuous service. When the passing of these years has told also a story of

important pioneer work, of purposeful achievement and steady progress, it becomes a record to conjure with. Of such is the repute that Professor Charles R. Cross has established in the long period of his association with the Massachusetts Institute of Technology, and of such the honor which the institute and all men are glad to accord him as he now lays hold upon the satisfactions of a well-earned retirement. Being graduated from Massachusetts Institute of Technology in 1870, with the third class that went out from its halls, Professor Cross forthwith returned after the summer vacation to take up an instructorship in the department of physics. Upon completing a single year of this service he was made an assistant professor and by 1878 had been given rank as a full professor. In 1886 he became director of the Rogers laboratory and in 1907 was made head of department. It is the threefold mantle of these responsibilities which he wears to-day and which he now contemplates laying aside.

Such accumulated funds of loyalty to his institution, of prestige not only in its counsels but in the scientific world at large, and such skill of investigation and analysis as Professor Cross has acquired, constitute a tangible fortune which might well be assessed only for its large present values. Yet if one is to take his career in review, there must be observed in particular the contribution Professor Cross made to the establishment of electrical engineering as an independent department of modern scientific and technical training. In the early eighties, some time before the wondrous expansion in the practical uses of electricity had generally been foreseen, Professor Cross prophesied it and insisted on electrical studies as part of his teaching in physics. He offered them long before they were taken up by other educators throughout the country, he developed their technique and bore the brunt of a pioneer's labor. Later it was at his instance that Technology introduced the first courses leading to a degree in electrical engineering ever offered in America. All through this development, his influence made for the increasing use and effectiveness of experiments in the illus

tration of lectures-that most important change of emphasis which came to pass in the method of scientific education. Professor Cross has won high place, which he will hold, whether or not in retirement.-Boston Evening Transcript.

SCIENTIFIC BOOKS

The Birds of Britain, their Distribution and Habits. By A. H. EVANS, M.A., F.Z.S., M.B.O.U., Cambridge, 1916. Svo, pp. xii+ 275, numerous halftone text-figures.

This concise and rather informal work is stated to be "primarily intended for schools," but is designed also to serve as a "short handbook which includes the results of the most recent observations, and is adapted to modern nomenclature." While this intention may be justified by the character of the main text, the introductory chapter, treating of "The Class Aves, or Birds in General," might have been written a generation ago, and does not include "the results of the most recent observations," as regards especially the subject of migration. Reference is made only to the creditable work of local observers in Britain, which has accumulated interesting facts regarding the movements of birds in England and Wales without furnishing generalized results, while the important work carried on elsewhere is passed without mention, including the researches of the late W. W. Cooke which have so greatly extended our knowledge of this subject.

The au

In the main text, under the general heading "Classification," with subheadings for the higher groups from orders to subfamilies, a paragraph, without special heading, is devoted usually to each species of regular occurrence in Britain, with a nominal list at the end of nearly 200 " occasional visitors" not formally mentioned in the preceding pages. thor manages to give in the half-page notices of the species of regular occurrence a comprehensive statement of their leading traits, distribution and diagnostic features, in a clear and direct way that should render his “little book" attractive and useful to many readers. The nomenclature is strictly modern, being

"almost exactly" that of the British Ornithologist's Union's revised Check-list. The illustrations, though said to be "from photographs taken for the most part from nature," are in many cases obviously not from life but from stuffed specimens or from museum groups, and are thus not up to the standard of the text. J. A. A.

SPECIAL ARTICLES FACTORS IN THE GROWTH AND STERILITY OF THE MAMMALIAN OVARY

1. THE growth and, to some extent, the structure of the mammalian ovary depend essentially on the development of the ovarian follicles. The maturation of some follicles and the subsequent rupture leads to the formation of the corpus luteum; the retrogression (atresia) of follicles before they have reached maturity and ruptured leads in certain species to the formation of the so-called interstitial gland and in others to the accumulation of atretic follicles in which the theca interna is

relatively prominent, without, however, the formation of an interstitial gland.

As we shall see presently, it is possible to inhibit the full development of the follicles experimentally. Under these conditions we find that the atretic follicles with relatively large thecæ internæ, are especially numerous and constitute perhaps the greater part of the ovary. We may therefore conclude that it is the pressure exerted by the developing, expanding follicles which leads to the shrinking and ultimate complete disappearance of the atretic follicles, and that if this pressure is diminished these atretic follicles become relatively prominent. This explains their relative preponderance in the guinea pig during the period following ovulation, when no large follicles are present in the ovaries.

2. Former observations of the writer showed that under certain conditions mitoses in the granulosa cells of the follicles were especially frequent around the ovum. This suggested the possibility that the stimulus for the growth of the granulosa cells which ultimately determines the growth of the whole follicles, depends upon a substance given off by the Dr. L. S. N. Walsh in our laboratory

ovum.

has recently shown quantitatively that during the whole course of the development of the follicles definite relations exist between the ovum and the proliferation of the granulosa cells. These relations can hardly be explained in any other way than as dependent upon a growth stimulus emanating from the ovum and determining the proliferation of the granulosa cells and thus indirectly of the whole follicle. It is possible that in addition to this endogenous growth stimulus certain exogenous stimuli, emanating from other organs with internal secretions (hypophysis?) may be operative. This effect of the ovum on the granulosa cells leads to the formation of the cumulus oophorus, and this structure makes possible the escape of the ovum into the Fallopian tube. Thus the ovum is ultimately the seat of the mechanism which makes possible its fertilization and fixation in the uterine wall.

3. In previous investigations1 we have shown that it is possible to cause a premature atresia of follicles by the burning out of the corpora lutea. While the effect of moderate heat does not directly destroy the follicles, it diminishes their expansive power; they grow up to a certain point and then become prematurely atretic; the heat causes a mild degree of what might be called a "tissue shock." Under those conditions the development not only of mature, but even of moderately sized follicles, does not take place and as long as this condition lasts the animal is sterile.

4. In continuation of these experiments we found that it is possible to produce the same condition not only by means of a local interference with the ovary, but also by affecting the general state of nutrition through underfeeding the animal. In all cases in which the animals (guinea pigs were used in our experiments) had lost 25 per cent. of their initial weight maturation of the follicles ceased, and in the majority of the cases the follicles became atretic before they had reached even medium size. The changes in the ovary were on the whole more pronounced in younger animals weighing between 300 and 400 grams,

1 Loeb, Leo, Zentralblatt f. Physiologie, 1911, XXV., No. 9. Virchows Archiv, 1911, CCVI., 218.

but in some cases very marked changes were also produced in older animals. A certain minimum time has to elapse before the changes in the ovary become apparent.

The lack of sufficient food affects in the first place the granulosa cells; they prematurely dissolve. Those granulosa cells, however, which at first escape the solution, continue, as Dr. Walsh found, to divide at approximately the normal rate-another proof of the distinctness of proliferative stimuli and foodstuffs.

The connective tissue becomes affected by the underfeeding somewhat later than the granulosa. This apparent difference in the resistance of different tissues to the effects of underfeeding is of interest and will be tested in further experiments. Thus underfeeding, if very marked, will lead to at least temporary sterility in the guinea pig as an expression of what we designated as a "hypotypical" condition of the ovaries.

5. In one case of pronounced loss of weight following thyroidectomy, we found a still further reaching change. Not only were the ovaries hypotypical, but the stroma separating the various follicles had become affected. It was underdeveloped or lacking in places, so that the thecæ internæ of neighboring follicles in places directly adjoined each other. As a result of this condition and of an imperfect separation of primordial ova, due to the same relative inactivity of the connective tissue, many follicles containing two or more ova developed in both ovaries. It could be clearly seen that small follicles were pushed into the cavity of neighboring follicles as a result of the intraovarian pressure, which, while diminished in hypotypical as compared with normal follicles, was still positive and as a result of the lack of development of ovarian stroma. Follicles containing more than one ovum are occasionally found in the ovaries of various species and it would be of interest to determine whether in addition to the factors operative in our case, other factors may be responsible for this condition in other cases.

LEO LOEB DEPARTMENT OF COMPARATIVE PATHOLOGY, WASHINGTON UNIVERSITY

SEGMENTATION IN nematoDES: OBSERVATIONS BEARING ON THE UNSETTLED QUESTION OF THE RELATIONSHIP OF NEMATODES TO OTHER BRANCHES OF THE

ANIMAL KINGDOM

I HAVE long been impressed by certain evidences of segmentation in nematodes. My first impressions arose from a study of the distribution of the setæ on aquatic forms. This distribution was in those days, and is even yet, described as irregular; the setæ are said to be "scattered" on the body. Charting all the setæ on a given specimen led to the conclusion that they were not scattered ("zerstreut "); that, rather on the contrary, they constituted a series of more or less harmonious groups. The cephalic setæ, it is well known, have an orderly arrangement. The study of a large number of cases leads me to the conclusion that those setæ, some distance behind the cephalic setæ, denominated subcephalic setæ, are also orderly in arrangement, and might, in some instances at least, be regarded as repetitive of the cephalic setæ.

Later I was able to show that the transverse striæ of the cuticle are retrorse on the posterior half of the body, and the reverse on the front half. (See Fig. 1.) This reversal in the cuticle at the middle of the body, or thereabouts, occurs in a very wide range of genera, is independent of age and of sex, and seems a character of fundamental significance.

FIG. 1. DIAGRAM OF THE REVERSAL OF THE STRIE OF THE CUTICLE OF A NEMATODE.

Recently I have discovered that the principal cephalic organs are made up of segments which, while simple in character, bear no small resemblance to corresponding features in arthropods. The nature of these segmented appendages will be more easily understood by consulting the illustrations in Fig. 2.

The articulations in the cephalic organs of nemas are not easy to discover, owing to the small size of the organs and the transparency of the tissues. Some of these segmented

organs are under muscular control, and can be extended and inflexed after the manner of the palps of insects. This is true of some of the labial organs, which unfortunately are usually so small as to be difficult to observe. The cephalic setæ, however, are larger, being particularly well developed on some marine forms, and in this case observation on living specimens affords evidence of the articulations when they might be overlooked if they were sought by other methods; for if a seta is obstructed it takes on the attitude natural to an organ composed of flexible joints and more or less inflexible segments, as shown in the upper illustration, Fig. 2. Here again, once having established the fact and learned how to make the observations, it proves that the setæ of a wide range of genera are jointed, though the number of segments is often reduced to only one or two.

FIG. 2. CEPHALIC SETA OF A NEMATODE, SHOWING SEGMENTATION. TWO DIFFERENT ATTITUDES OF THE SAME SETA.

One recalls that a number of observers have noted the presence of longitudinal series of repetitive organs in the lateral fields of nematodes, though attention has never been called to the fact that these organs on opposite sides of the body may be symmetrical to each other. Sometimes they are exactly so.

N. A. COBB

SOCIETIES AND ACADEMIES THE BOTANICAL SOCIETY OF WASHINGTON THE 119th regular meeting of the Botanical Society of Washington was held at the New Ebbitt Hotel, on March 14, 1917. Seventy-four members and sixty-five guests were present. After a dinner President T. H. Kearney introduced the re

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