Kiær looks upon the spines of the Anaspida and the lateral lobes of the Cephalaspidae as homologous with paired fins and as originating in lateral fin folds. The absence of any homologue of the pelvic appendages is believed to be primitive. As regards the affinities of the group the following views are advanced: (1) He concurs in the "general view" that the Acrania, Cyclostomata and Pisces form three ascending stages in the development of the Chordata (although, to be sure, the Acrania and Cyclostomata as we know them are specialized and to some degree degenerate). (2) The dermal skeleton was characteristic of a normal stage in this development. The earliest forms were naked, then arose a scale system governed largely by the mechanics of the lateral muscle plates, and passing by later development into various specializations, such as fusion into plates, as in the ostracoderms, or on the other hand reduction or loss. (3) The unpaired nasal opening and pineal organ, their grouping with the eyes and the structure of the branchial apparatus are believed to be the most important structures of the Anaspida. Now in all these characters they resemble the cyclostomes (Petromyzontia) and furthermore these are just the characters which separate the latter from the true fishes. The unpaired nasal opening is considered especially fundamental and Haeckel's grouping of all vertebrates into Monorhina and Diplorhina is revived. Hence the Anaspida are believed to belong to the same group of monorhine craniates as the cyclostomes. The absence of a dermal skeleton, jaw structures and paired pectoral appendages in the latter are considered secondary due to degeneration. (4) As to the other groups usually united under the designation Ostracodermata, the Cephalaspidae are close relatives of the Anaspida. Pteraspidae and kindred forms (Heterostraci) are, however, very different, and it is considered probable that they are related to the Elasmobranchii, as Traquair believed. As for the Antiarchi, these forms are so isolated as to be altogether uncertain in position. They can scarcely be assigned any close connection with the Arthrodira and are in any event diplorhine and true fishes. An outline of the classification which concludes the work may be given here: Subphylum Vertebrata Craniata. Branch I. Monorhina. Class I. Anaspida: Lasaniidae, Birkeniidae, Pterolepidae, Rhyncholepidae, Class II. Cephalaspidomorphi. The fourteen plates are reproductions of photographs and bear abundant witness to the wonderful preservation of the material. The theoretical conclusions of this monograph will undoubtedly give rise to much discussion and some differences of opinion. There is, however, no room for discussion as to the painstaking and accurate nature of the work nor as to its meriting the high praise and wide notice which it will undoubtedly receive. The gaining of a thorough knowledge of these members of the Anaspida, a group so ancient and so fundamental as to be of the highest interest for any student of vertebrates living or extinct, is an event of the very first magnitude. PEABODY MUSEUM YALE UNIVERSITY G. G. SIMPSON SCIENTIFIC APPARATUS AND LABORATORY METHODS REACTION OF OPALINAS TO VARIOUS LABORATORY MEDIA PHYSIOLOGICAL salt solution has for many years been the traditional and all but universal medium in use for maintaining organisms and tissues in biological laboratories. In a series of experiments on Opalina obtrigonoidea, begun for another purpose, we have however found, rather contrary to our expectations, that physiological salt solution is not as efficient as several other common laboratory media for keeping Opalinas alive. By the use of Locke's solution, 50 per cent. sea-water, etc., Opalinas may be kept alive for a considerable length of time outside of their natural habitat in the cloaca of the leopard frog (Rana pipiens). It has been observed in a number of other instances that sea-water of various concentrations is an excellent medium; this has also proven true in our work on Opalinas. In our experiments it has been observed to be almost on a par with Locke's solution, which we found to be the best of all the solutions we used. Eight different media were tried with varying results as shown in the table below. These results we hope will be of interest to teachers of biology who wish to demonstrate or study such parasitic protozoa as are found in frogs. All the protozoa that one may desire may be obtained from frogs used for other class purposes. This may easily be done by removing the cloaca from a freshly killed frog and opening it in a watch glass half filled with the desired medium. The most satisfactory results are obtained by dividing the material among two or three dishes so that each dish has a piece of the cloaca and a part of the cloacal content. The watch glasses should be kept covered to prevent too great evaporation and consequently too great concentration of the salts. The Opalinas in such a solution may be expected to remain alive and in good condition for two days or more and in the case of Nyctotherus for as long as six days. The above solutions are easily made up and seawater may be readily obtained at any biological supply station or be made synthetically according to Mayer.1 A more complete report on the longevity of Opalina obtrigonidea in various media together with other observations is in preparation for publication later. MARY E. LARSON MAMIE HOPE VAN EPPS STANLEY T. BROOKS ZOOLOGICAL LABORATORY OF SPECIAL ARTICLES SURFACE TENSION DETERMINED BY THE RING METHOD In recent years a considerable amount of attention has been given to the problem of finding a method by means of which the surface tension of a liquid can be measured rapidly and with some degree of accuracy. An apparatus in which the pull on a ring is measured by means of the torsion of a wire evi1"The relation between degree of concentration of the electrolytes of sea-water and rate of nerve-conduction in Cassiopea," by A. G. Mayer, from Papers from the Tortugas Laboratory of the Carnegie Inst. of Wash., Vol. VI, 1914. Publication No. 183. dently meets the requirements of convenience and rapidity. Such an apparatus has been devised by du Noüy.1 According to the simple form of the theory underlying the use of the ring method, the surface tension of the liquid is equal to the pull on the ring at the instant of rupture of the films of liquid divided by twice the circumference of the ring. Unfortunately the values obtained in this way are certainly too high. Paul E. Klopsteg2 has attempted to explain the high values obtained by the method of the torsion-balance on the ground that as the ring is lifted out of the liquid the zero of torsion no longer corresponds to the zero of the scale. He suggests that as the torsion on the wire is being increased the vessel containing the liquid must be lowered so that the arm will at all times be in its position of zero-balance. This procedure is undoubtedly correct. But I do not think that the simple theory of the experiment even with the procedure advocated by Klopsteg can lead to accurate values of the surface tension. It is well known that, after the ring has been detached from the liquid, droplets frequently adhere to it. Klopsteg suggests that a correction must be applied by adjusting the zero-balance of the instrument with the droplets adhering to the ring. I hope to show that the magnitude of the pull on the ring is independent of whether droplets are formed on the ring or not. In this discussion I shall use the following symbols: During the last two or three years, Dr. R. G. Green, of the department of bacteriology, has been carrying out measurements with platinum rings having values of r from .015 to .05 cm and of R from 0.3 to 1.3 cm. We soon found that the value of p is a function of r and R, increasing rapidly with increase in r and diminishing slightly with increase in R. We also observed that a maximum pull is reached before the film breaks. If there is in fact a maximum pull, it is evident that its magnitude will be independent of such phenomena as the actual breaking of the film and the adherence of droplets of liquid to the ring. At this stage in our studies, I came across an ar 1 Journal of Gen. Physiology, I, 521–524 (1918–19). 2 SCIENCE, October 3, 1924. ticle by M. Cantor3 in which the present problem is treated in a very complete manner. This article seems to have been overlooked by recent writers on the subject. I shall therefore present some of the results obtained by Cantor and discuss the range of their validity, assuming for the sake of simplicity that the liquid and the ring have zero "contact-angle." At any stage in the process of detaching the ring from the liquid, imagine a vertical plane passing through a diameter of the ring and giving a circle as crosssection of the wire. The inner and outer films may touch this circle at the points A, and A2. If O is the center of this circle, let OA, and OA, make angles Y1 and Y2 with a radius drawn vertically downwards from O. Let k be the height of the lowest part of the wire, and let y1 and y2 be the heights of A, and A, above the general level of the liquid. Let y and y be the corresponding values as R approaches infinity. Cantor assumes (1) that r is small in comparison with R; (2) that R is sufficiently large to make it possible 1+2 How large R Y1+2 and Y 2 2 to write y= must be to satisfy these conditions, we shall discuss later. With these assumptions, Cantor obtains the equations: p= a sin Y + krsg siny + r2sg 2 1 -[sin y (2 – cos y)- Y] Y1 or y2 we neglect terms in and higher powers R2 R® a2 Now this term in will have the same sign R2 √sg (1 + cos y) -r(1-cos y). These equations, which I submit with some reservation, would indicate that the error committed in using equations (A) or (B) will not amount to more than a2 one per cent. if the term 0.040 is not greater R2 than 0.01; in other words if R is greater than 2a. In experiments with water, therefore, R should be greater than 0.75 cm. л+3 a=p-r V2psg + r2 sg (B) 4 SCHOOL OF CHEMISTRY, 3 Capillaritätsconstanten, Wied. Ann. 47, 399-423 (1892). UNIVERSITY OF MINNESOTA, MINNEAPOLIS, MINN. F. H. MACDOUGALL SEX DIFFERENCES IN EMOTIONAL OUTLETS BEFORE reliable measures of intelligence existed it had been generally assumed that women were less intelligent than men. When these alleged differences in intelligence are measured, however, they have been found on the whole to be practically negligible, if, indeed, there be any consistent sex differences. Recent test development has made it possible to make similar measures of the alleged differences in the emotional natures of the sexes. We have recently compared about six hundred college men with about four hundred college women on the Colgate mental hygiene tests. These are tests of indirect emotional outlets which are indicative of mental or emotional instability. There are forty-eight items of behavior pertaining to introversion in the tests. College women we find much more introvert than college men, the average woman appearing to be about 10 per cent. more introvert. This means that women tend-or may be forced to live their emotions largely within their own mental sphere, while the men live their emotions more in associating with others. There are thirty-two traits of psychasthenia in the tests. The women are more inclined toward this spurious mental fatigue, being on the average about 20 per cent. more psychasthenic than the men. Neurasthenia is tested in twenty-two items of the tests. Again we find the women with an excess of these indirect emotional outlets, although not to so marked a degree as they were in psychasthenia. In signs of hysteria there have been no demonstrable differences. This may be due to the tests lacking validity in the section dealing with conversion outlets. The reliability of this section is about .95, but the validity is low. The reliability of the other sections is above .8, and the validity is high. The unfavorable showing of women on these tests may be due in part to some selective influence rather than to any inherent differences by and large. Can it be that emotionally unstable women are attracted to college? In 1910, which is the last year with available figures, one out of every 1,416 men from twenty to twenty-four years of age and one out of every 1,815 women of the same age range were admitted to a state hospital as a mental patient. Among twentyfive thousand college students in 1923-24 the ratio was one man per 1,079 and one woman per 876. Among the general population the incidence of extreme emotional instability as typified in a psychosis is greater among men. Among the college population, however, the incidence is greater among women. This may be due to the age group from the general population being slightly older than the college population. Or it may be due to the woman inclined toward emotional instability entering college. In practically every instance statistics record an excess of male over female psychoses, both in absolute numbers and in ratio to the general population. Typical figures are those gathered from twelve states in 1919 by the National Committee for Mental Hygiene. These showed one male from each 1,105 of the total male population and one female from each 1,199 of the general population admitted to a state hospital during the year. This shows a slight and perhaps insignificant predominance of psychoses among men. Five Some psychoses are the product of physical forces in the environment rather than of indirect emotional outlets. Eight times as many men, for instance, were confined because of traumatic mental disorder. times as many men suffered general paralysis, caused by social disease. On the other hand over three times as many women had mental disorder associated with pellagra. These psychoses due to exogenous influences should be eliminated in comparing the inherent emotional differences of the sexes. When these are eliminated the ratio is one out of 1,444 men and one out of 1,355 women. When the psychoses due fairly directly to environmental factors are excluded the balance shifts in favor of the male. This may confirm the findings on the mental hygiene tests and indicate that the college incidence rate of psychoses fairly represents the true conditions with the sexes under somewhat more similar environmental stresses than exist outside of the cloistered seats of education. Granting, however, that when the present environmental stresses are equalized among students there is a preponderance of undesirable emotional outlets among women we have yet to demonstrate that the difference is inherent in sex. From earliest childhood the restraints and training of the sexes differ and the difference we find in middle adolescence may be a reverberation of this early environment. Our data can not be interpreted as showing that there are innate differences, the differences may be acquired. The trend of opinion is that the emotional outlets such as we are testing are acquired. Data are being gathered which bear on this point. The very practical problem of an effective difference remains, regardless of its origin. COLGATE UNIVERSITY DONALD A. LAIRD THOMAS MCCLUMPHA PSYCHOLOGICAL LABORATORY SCIENCE THE RÔLE OF EPITHELIUM IN EXPERIMENTAL IMMUNIZATION1 SOME twelve years ago I became impressed with the idea that the surface epithelium of the body, including the epidermis and the succulent coverings of the respiratory and alimentary canals, must have important functions in mediating between foreign material brought in contact with it and the internal tissues which it covers.2 From either a physiological or pathological point of view the surface epithelium forms the "first line of defense" of the body. Our modicum of knowledge respecting the protective attributes of this covering embraces two certaintiesthat it is a mechanical barrier intervened to the passage of foreign material, especially when particulate; and that, when part of a mucous membrane, it is a metabolizing organ capable of chemically changing foreign substances in contact with it. And yet, in the vast majority of experiments designed to elucidate the reactions of the living tissues toward such materials, these are introduced by traumatic methods avoiding the first line of defense. An animal might conceivably live long without ever suffering a lesion through which foreign matter might be absorbed, but no mammal has ever escaped the necessity of swallowing or inhaling extraneous substances, including proteins which act as antigens when introduced as such within the body. The following observations are concerned in no way with reactions of the alimentary canal but only with the mucous membrane of the nasal chambers. The fact is sufficiently extraordinary that, in the healthy subject, the epithelium of the lungs and bronchi is free from microorganisms, untold numbers of which daily enter the nose. What has become of them? What chemical changes have attended their destruction? What tissue reactions have answered the absorption of such foreign proteins or their digested products? It seems plausible that "natural immunity" might find its extraneous stimulus in such conditions of antigenic absorption. For three years, with the invaluable cooperation of my colleague, Dr. Cuthbert Powell, I sought to outline experimentally the immunological attributes of the 1 Chairman's address, Medical Section, Southwestern Division, of the American Association for the Advancement of Science, Boulder, Colorado, June 9, 1925. 2 Sewall, H., Archives of Int. Med., 1914, XIII, 856. |