known method their accurate position in relation to the rest of the body can be determined only with the greatest difficulty. Even while dissecting in the most. careful and exact manner, one can not avoid cutting off some very fine points of the ribs or projections from some other bones. An X-ray picture makes this unnecessary. The X-ray picture would be especially valuable for studying fossils; above all for the study of fossil fishes. An X-ray picture resembles such a fossil much more than a skeleton without any of the soft parts could possibly do. While these parts are rather dim on the negative, they are sharply circumscribed and remind one of the shape of the fossilized animal, whose outlines and soft parts of the body can only be distinguished by a discoloration of the stone. In differentiating a number of closely related species of the same genus, whose only differences consist in colors and small dissimilarities of the body, the paleontologist is faced with an extremely difficult problem. It might be said that, in the meaning applied to living species, such a procedure is futile. By means of X-ray pictures real species distinguish themselves through constant differences between each other (small differences of the skeleton, in the air-bladder, etc.). These differences, however, in many species are so inconsiderable that we can hardly use them as a basis for distinguishing paleontological species, if we consider that the fossil print incorporates a number of changes and disturbances of the several parts of a body. In studying the skeleton, the possibilities of biological investigation are by no means exhausted. Even the usual X-ray picture shows that the soft parts of the body appear on the negative in varying degrees of intensity. On fishes, for instance, the air-bladder will appear very clear and sharply outlined, especially if the picture has been taken immediately after the death of the animal. A procedure, so generally adopted in medical practice, to inject certain solutions or emulsions into cavities on account of their relative impermeability to X-rays in order to make them visible on the negative, points a way to a method which has been hardly used at all. I injected barium sulfate solutions into the heart and the larger vessels of fishes and obtained pictures which are clear to the most minute detail; many show even the last capillary vessels absolutely plain. That in such pictures each vessel will be shown in its true position and relation to the rest of the body goes without saying. Here again the advantage of saving a great amount of time and work is apparent. Biologists are well aware that investigations involving the smaller vessels demand preparations which involve months of painstaking technical work. I know of a distinguished scientist whose studies of the position and relations of the smaller vessels of the human heart demanded years of his time. An X-ray picture of a properly injected organ might have shortened that time to a few hours. It is possible to make just as easily studies of the vessels of invertebrate animals. As a matter of fact, these promise even more success, because there are no skeletons to disturb the picture. The practice of using certain selective staining methods for representing certain elements of the body-for instance, the nervous system-seems to me to be altogether within the limits of adaptation. In the same manner as vessels, other cavities can be shown by means of injections. Here is the main field for roentgenographical work in botany. Also the entomologist, who studies plants that have been attacked by insects, will surely find in X-ray pictures a valuable help. Naturally each field of investigation and its peculiar technic must be studied in all its particulars. The representation of the blood vessels, too, necessitates certain preliminary conditions and a certain practice which can be acquired only through experience. In a forthcoming paper I am discussing the methods and advantages of X-ray pictures as applied to zoological and botanical materials. The use of this method is fully demonstrated in a monograph on Hawaiian fishes, now in preparation. VICTOR PIETSCHMANN MUSEUM OF NATURAL HISTORY OF VIENNA A CONVENIENT. METHOD OF DETERMINING THE RATE OF CLEAVAGE FOR the study of factors influencing the rate of cleavage of developing eggs, it is essential to determine that rate for a large number of eggs. Since the individual differences in the time of cleavage usually extend over a period of only a few minutes, the counting has to be done quickly. The inexperienced worker will have to spend some time in acquiring the necessary skill for obtaining reliable data. The following convenient and accurate method is suggested. The camera lucida is used. Note the time of the appearance of the first cleavage of the eggs in the microscopical field, and from now on mark on the drawing paper, with the aid of the camera lucida, all those eggs that divide within the first two minutes with No. 1 written across the image of the egg. Eggs dividing within the next two-minute period, mark with No. 2, and so on until the whole field has divided. A record is left on the paper. Now count from this record the number of eggs marked with 1, 2, 3, etc. You thus obtain the data for a regular distribution SPECIAL ARTICLES THE EFFECT OF A SECONDARY SOUND UPON HEARING THE problem of hearing in the presence of a secondary sound has of late received considerable attention from correspondents of this journal. The ancient belief that certain persons suffering from paracusia, in the form of a partial deafness of the conduction-type, are able to hear more acutely in noisy surroundings than under conditions of quiet has been brought to question and debated on various sides.1 The matter seems at last to be decided by the excellent experiments of Knudsen and Jones, reported recently. The threshold of hearing was ascertained for speech-sounds and for a faint tone both in silence and with a constant noise, and it was shown that for all subjects, normals and defectives alike, acuity is reduced in the presence of a noise. This finding is not incompatible, it must be noted, with the wellattested fact that under particular conditions the paracusic can carry on conversation more easily in the presence of a secondary sound. The phenomenon is a consequence not of an increased sensitivity of the acoustic mechanism, but rather of a relative advantage which the situation affords the paracusic over his normal companion. The explanation is plain. The commonest auditory defects involve a considerably greater reduction of low tones than of high tones, and since most extraneous noises are made up predominantly of low-pitched tones, it follows that the person of impaired hearing is deaf to the secondary sound relatively more than he is to the essential tones of speech (which are of higher pitch) and thus in conversation is disturbed by the sound relatively less than is a person of normal hearing. Now since the loudness of one's voice is adjusted by reference to the background as he hears it, the normal person, being greatly disturbed 1 See, e.g., 60 (1924), 360; 61 (1925), 260 ff.; 62 (1925), 109-111 and 182; and esp. Kranz, 60 (1924), 549. 2 V. O. Knudsen and I. H. Jones, Laryngoscope, 36 623-663. (1926), by a sound, speaks much louder than usual, but the defective, selectively deaf to the sound, raises his voice but little. The net result of the background, in this situation, is a favoring of the person of impaired hearing, though actually the acuity of both persons is reduced as compared with silence. This explanation is supported by the fact that the illusion of improved hearing in the presence of a noise occurs only in conversation between a normal and a defective, and never between two normals or two defectives.3 All this seems clean-cut enough. The writer has merely to add some remarks upon an experiment which in a measure confirms, and further extends, the findings of Knudsen and Jones and which brings forth an additional problem for settlement. The experiment, conducted at the University of California last year in collaboration with Mr. Stanley R. Truman, was concerned with the effect of a background of tone upon the acuity of the normal ear. Various frequencies and intensities of tone were used for the background and for the testing-tone, and we found, as Knudsen and Jones did, that at the introduction of a tonal background hearing is always reduced. However, we came upon the further discovery that the threshold does not remain constant under such conditions. At the entrance of the secondary tone the acuity is considerably diminished, but recovery of sensitivity begins immediately and proceeds at a rapid rate until, under a given set of conditions, it may become three or four times as great as it was at first. Sensitivity does not, however, reach the level shown under conditions of silence; after about two minutes it has attained its highest extent and from then on we found no indication of further significant change. Just what is the cause of this change in thresholdsensitivity we are thus far unable to state with conviction, but experiments are in progress which it is hoped will afford a clue. It would be interesting as well as significant in this relation to know whether paracusics would show the same type of curve of threshold-recovery as do normal persons under the conditions stated, and whether with prolonged stimulation by a secondary tone the relative advantage which, as has been pointed out, circumstances may afford the paracusic would continue to be maintained. Unfortunately, Knudsen and Jones do not tell us the temporal conditions of their tests, and the presumption is that they took no pains to control themthough it is plain on the basis of our results that the temporal factor is of first importance. It is to be hoped that some investigator with the necessary elinical facilities will extend the work of Knudsen and 3 See Knudsen and Jones, ibid., and cf. H. Fletcher, Volta Rev., 26 (1924), 443 f., 447 f. 4 See J. Exper. Psychol., 11, 1928, 98–112. Jones, and trace the sensitivity of the paracusic ear in the presence of a tonal background throughout its course of change; the result might lead us to a better understanding of this phenomenon not only in paracusia but in normal hearing as well. E. G. WEVER PRINCETON PSYCHOLOGICAL LABORATORY, PRINCETON, N. J. REMARKABLE MUSICAL TECHNIQUE OF THE LARGER ANGULAR-WINGED KATYDID It is evident that there has been marvelous specialization in the vocal music of the birds, the flute-toned thrushes, including the marvelous hermit, probably leading them all with their tonal embellishments. There has been a parallel specialization among the musical insects of the world. The insects have turned especially to instrumental music, adopting microscopic teeth to be operated upon by a scraping edge as the more common type for their frictional music, in the majority of instances. A mere file-vein and scraper or plectrum to rasp across its teeth seem simple enough as a musical instrument, but even this primitive chitin xylophone offers many possibilities of specialization. It may have teeth of different sizes and spacing, to produce different notes as in the case of certain soundmaking ants and beetles, or more than one file-vein may be present on an insect. For the present these specializations of the physical structures of the instrument itself need not be considered. There is a further possibility, and that concerns the technique, the manner of handling the instrument to produce the greatest variety of tones and notes. In the music of man, technique has become the big factor, and marvelous progress has been made in this direction alone by the modern masters over the ancients. In spite of the fact that the crickets have somehow hit upon tonality in their music, and the katydids have not, the latter have nevertheless shown a marvelous specialization in the direction of technique far excelling the crickets. The larger angular-winged katydid has proven himself a master-artist with his xylophone. He has specialized in a manner that makes him a pioneer in his art, at least in our own country. Unfortunately we know too little of the musical behavior of insects elsewhere in the world. This fine katydid, as veritably leafadorned as the trees themselves, has somehow learned of the full potentialities of his microscopic file-vein and is making good use of his acquirement. The filevein is a mere thickened ridge or vein bearing parallel chitin bars or teeth, like the teeth of a comb, these being set practically at right angles to the vein and perpendicular to the surface from which they arise. An almost universal technique among the crickets and katydids is to draw the scraper entirely across this music-file one or more times to produce a note. In the single chirp of a cricket or the intermittent rasp of many katydids, an extremely rapid back-and-forth movement several times delivered produces the sound. The quaver of the cricket-chirp is due to these alternate wing-strokes. In this manipulation all the teeth of the file-vein are used practically simultaneously. The larger angular-winged katydid has somehow gone far beyond this and has learned to produce a long, slow crepitation of thirty to forty or more clicks, making use of the individual teeth, or perhaps sometimes slipping over two or more teeth. The wing-covers along their upper edge are opened nearly three sixteenths of an inch, and set at an angle that will bring the file-vein of the under side of the upper tegmen against the scraper of the upper side of the under tegmen. The scraper is now slowly moved with nice adjustment and precision over the individual teeth, in a gradual closing movement of the wings to produce the long series of individual clicks characteristic of the more typical "song" of this species. A count of the teeth of the file-vein, including poorly-developed ones at each end of the file, reveals only from fifty-five to sixty teeth, in a length of about three mm. It is probable that not many more than forty to fifty well-developed teeth are present on this file, which would allow not more than an average of one tooth per click in a series of thirty to forty clicks. This is a remarkable specialization in technique and shows the nice control of the katydid in this behavior. It would appear that no other katydid or cricket in our own country has progressed this far in the matter of technique, and we know as yet too little to speak with any authority covering the technique of any foreign species. This katydid not only makes use of this specialized technique, but it has in addition an intermittent zip, produced by striking all the teeth with one quick draw of the scraper across the teeth. One wonders how this fine katydid sensed this new technique of tapping the chitin-bars of its dorsal, organic xylophone very slowly, to make each tooth emit a note or tone. The most marvelous thing about life, however, is the way it always seems to sense possibilities in every detail of form and function. Once the chitinous xylophone came into being on its wingcovers, once the scraper began to touch the bars to produce a rasp, potentialities were ahead. In the case of the intermittent rasp or zip of this katydid, one quick closing draw produced the note. Slowing down this closing draw of the scraper upon the file-vein was the next step, and some weird prescience of life has in some manner taught the katydid to do just this. While the crickets have evolved tone in their musical expressions, the matter of technique such as the katydids have specialized upon, seems quite beyond their moods at present. Yet if any of our crickets could strike pure musical tones upon the individual chitinbars, as the larger angular-winged katydid is attempting to do with its sounds, their tinkling chimes would mark a new era in the spontaneous expressions of insects. A number of the katydids have evolved complicated little instrumental "songs," involving wide departures in time-relations and variety of phrases, from the simple repetitive rhythms of the more primitive type. All this marks some unconscious specialization, it would seem, toward a fuller self-expression with the potentialities of sound. It is hard to see just how an uncouth and prehistoric scaled-reptilian type should evolve into a beautiful bird, feathered, songful or finally into an inimitable hermit thrush with a soul sensitized for music or pleasurable sounds and whispered tonal harmonies. Yet the lowly insects with their primitive musical instruments, a simple file-vein and scraper, are following the same trend, it would seem. Tonality they have, in the case of the crickets; highly specialized technique and variety they have in the case of the katydids; rhythm and even an ear for synchronous rhythm is evident in both great groups. Is it something unconscious, external and cosmic operating upon life, or is there a subconscious urge, which sooner or later becomes translated into the conscious experience of life? Surely, now are the crickets and katydids conscious of their sound-experiences, but the methods, the genesis of it all constitute a mystery as deep as life itself. The individual seems to have as little to do with it all as the individual cells of our bodies have to do with our own running, our talking, seeing or what-not in body-behavior as a whole. The organic unfolding of the phylum at times seems to be the unit, with the individual functioning as a mere cell in its continuity, but this savors too much of the ultimate meaning of life of which we can have no adequate concept. U. S. DEPARTMENT OF AGRICULTURE, WASHINGTON, D. C. H. A. ALLARD SOCIETIES AND ACADEMIES THE KENTUCKY ACADEMY OF SCIENCE THE Kentucky Academy of Science held its fifteenth annual meeting at the University of Kentucky May 12, President Valleau presiding at the general sessions, at one of which Dr. E. C. Stakman, of Minnesota, representative of the American Association for the Advancement of Science to the academy, delivered a very interesting lecture on biologic specialization. The three divisions, biological sciences, physical sciences and philosophy and psychology, had full programs of papers. Officers elected were: G. Davis Buckner, University of Kentucky, president. George D. Smith, Eastern State Normal School, Richmond, vice-president. A. M. Peter, University of Kentucky, secretary. Division of Physical Sciences—W. R. Jillson, chairman; Division of Biological Sciences-G. D. Buckner, chair- THE NORTH DAKOTA ACADEMY OF THE twentieth annual meeting of the North Dakota Academy of Science was held at the North Dakota Agricultural College on May 4 and 5. Dr. H. L. Walster, dean of the School of Agriculture of the North Dakota Agricultural College, presented the president's address on the theme "The Pursuit of Science in North Dakota." A notable feature of the program was the showing by Mr. Russell Reid, of the North Dakota State Historical Society, of a series of fifty colored lantern slides showing the beauty spots in western North Dakota and illustrating the characteristics and nesting habits of many North Dakota birds. In his invitation address on "The Biological Value of Practical Agricultural Experimentation," Dr. J. Arthur Harris, head of the department of botany of the University of Minnesota, urged the point of view that much of the material results from agricultural experimentation could, through careful biometrical analysis and similar studies, be made to yield much material of great value in pure science. The following officers were elected for the ensuing year: President-Dr. G. A. Talbert, professor of physiology, University of North Dakota. Vice-president-Dean R. M. Dolve, school of mechanic arts, North Dakota Agricultural College. Secretary-Treasurer-Dr. G. A. Abbott, professor of chemistry, University of North Dakota. Additional members of Executive Committee: Professor J. H. Seymour, Valley City State Teachers' College; Professor C. H. McLees, School of Forestry, Bottineau. Representative of the North Dakota Academy of Science on the council of the American Association for the Advancement of Science-Dr. H. L. Walster, dean, School of Agriculture, North Dakota Agricultural College. SCIENCE THE DIFFERENTIATION OF SPECIES1 WITH the lapse of another year, it is again my privilege and my obligation to present what is technically known as a "presidential address." This occasion is one of particular personal interest, for it marks the close of continuous active service to the academy throughout a period of more than three decades, during which it has been my privilege to serve in almost every designated capacity. And with the close of this evening, I shall pass to the long and venerable list of ex-presidents, however unworthy that association may be with the notable men of science of our community who have directed the life and work of our institution. A choice of subjects is inevitably controlled by circumstances; the topic must be general in scope, it must be of timely interest, and it ought to be one with which the speaker is familiar, at least to some extent. I have chosen to discuss briefly some aspects of evolution. No other is more comprehensive or more fundamental. Each of the natural sciences, with its own materials and by its own methods, has demonstrated the reality of incessant change, in the heavenly bodies, in mountains and seas and continents, and in the wide array of plants and animals that constitute the organic world. The further circumstance determining this choice is the fact that for more than twenty odd years I have been engaged in the study of a definite group of animal organisms in an effort to understand the processes by which evolution comes about in wild nature. The natural history of animals is like that of plants, and hence this topic is directly related to botanical generalization. It is of real concern to the geologist also, who, as paleontologist, must deal with the bygone organisms that have lived and have passed away. It is axiomatic, of course, that the student of fossil species can not observe directly the dynamics of specific evolution; what he may know about the actual processes of transmutation can be learned only by the study of existing organisms and their changes, which he then projects into the past-precisely as the geologist can not see his age-old strata in process of 1 Address of the retiring president, delivered at the annual meeting of the New York Academy of Sciences, December 19, 1927. Photographic illustrations of topographic features, specimens and tabulated statistics, which were employed at the time, are necessarily omitted here. |