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. AN EYELESS DAPHNID, WITH REMARKS ON 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. was Unfortunately this individual discovered 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.'' 8. H. Blumberg, "New properties of all func- 9. E. B. Van Vleck, "On non-loxodromic substi- 10. G. A. Miller, "An overlooked infinite system 11. L. E. Dickson, "Fallacies and misconceptions 12. L. E. Dickson, "A new method in diophantine 13. T. H. Hildebrandt, "On a general theory of 15. J. B. Shaw, "Generational definition of linear 16. J. B. Shaw, "On Hamiltonian products-Sec- 17. F. E. Wood, "Congruences characterized by 18. E. P. Lane, "A general theory of con- Professor Schwatt's papers were presented by ARNOLD DRESDEN, Expense, travel 208.50 Printing 133.40 Membership campaign These disbursements have been made from funds derived Affiliated societies (assess- ments) Initiation fees Receipts from the Permanent 76.25 $1,687.42 115.00 163.00 1,409.42 $1,687.42 W. W. SARGEANT, Secretary, Pacific Division ADMISSION Candidates for admission must be graduates of approved colleges or scientific schools with at least two year's instruction, including laboratory work, in Chemistry, and one year each in physics and biology, together with evidence of a reading knowledge of French and German. Each class is limited to 90 students, men and women being admitted on the same terms. Except in unusual circumstances, applications for admission will not be considered after July 1st. If vacancies occur, students from other institutions desiring advanced standing may be admitted to the second or third year provided they fulfill all of our requirements and present exceptional qualifications. The charge for tuition is $250 per annum, payable in three instalments. There are no extra fees except for rental of microscope, certain expensive supplies, and laboratory breakage. The annual announcement and application blanks may be obtained by addressing the Dean of the Johns Hopkins Medical School Washington and Monument Sts. BALTIMORE, MD. SUMMER WORK FOR GRADUATES Beginning Tuesday, June 6th, and ending Thursday, July 16th, a course in medical diagnosis, including laboratory exercises in clinical pathology and demonstrations in pathological anatomy, will be offered. The course will be limited to twenty students, fee $100. Applications should be made to the Dean's Office. Louisiana SCHOOL OF MEDICINE (Established in 1834) ADMISSION: All students entering the Freshman Class will be required to present credits for two years of college work, which must include Chemistry (General and Organic), Physics and Biology, with their laboratories, and at least one year in English and one year in a modern foreign language. COMBINED COURSES: Premedical course of two years is offered in the College of Arts and Sciences, which provides for systematic work leading to the B.S. degree at the end of the second year in the medical course. School of Pharmacy, School of Dentistry and Graduate School of Medicine also. Women admitted to all Schools of the College of Medicine For bulletins and all other information, address Tulane College of Medicine P. O. Box 770 New Orleans, La. Stanford University Medical School The Medical School of Leland Stanford Jr. University is an integral part of the University, and its Faculty controls the Lane and the Stanford University Hospitals, which together with the Lane Medical Library, are administered by the Trustees of the University. Admission Instruction Tuition Three years of University instruction, in- For information address THE DEAN of the Stanford Univergity Medical School, 2398 Sacramento Street, San Francisco, California. Marine Biological Laboratory Woods Hole, Mass. INVESTIGATION Facilities for research in Zoology, Entire Year INSTRUCTION June 29 to August 9 1921 SUPPLY DEPARTMENT Open the Entire Year Embryology, Physiology, and Botany. Eighty-four private laboratories, $100 each for not over three months. Thirty tables are available for beginners in research who desire to work under the direction of members of the staff. The fee for such a table is $50.00. Courses of laboratory instruction with lectures are offered in Invertebrate Zoology, Protozoology, Embryology, Physiology and Morphology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $75. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is also offered. Animals and plants, preserved, living, and in embryonic stages. Preserved material of all types of animals and of Algae, Fungi, Liverworts and Mosses furnished for classwork, or for the museum. Living material furnished in season as ordered. Microscopic slides in Zoology, Botany, Histology, Bacteriology. Price lists of Zoological and Botanical material and Microscopic Slides sent on application. State which is desired. For price lists and all information regarding material, address GEO. M. GRAY, Curator, Woods Hole, Mass. The annual announcement will be sent on application to The Director, Marine Biological Laboratory, Woods Hole, Mass... |