thus given, only a few minutes were needed to get the analytical one." (Sub-Conscious Reasoning, Proc. S. P. R. pp. 11-13).—A. B. "The Mimetic Origin and Development of Bird-language," and "The Evolution of Bird-song."-When one considers how many people are thinking at the same time, it does not seem strange that two persons, though widely separated and totally unknown to each other, should sometimes think not only of the same subjects but also follow in the same direction and practically at the same time, the same lines of original thought and investigation. Some of these duplicated ideas are of value in commerce; others are mere metaphysical speculations, possibly suggested by the same incidents; but at this late stage in the knowledge of natural history it does appear unusual that two people in different hemispheres and observing totally different species of animals should have simultaneously pursued independently the same far-reaching but novel line of speculative thought. A few days ago, Mr. J. E. Harting called my attention to an article in THE AMERICAN NATURALIST, entitled "The Mimetic Origin and Development of Bird-language," which appeared in that journal for March, 1889. He did so because I had lately written a book on the subject, The Evolution of Bird-song (London, A. & C. Black, May, 1896), and because the article in question discussed some of my themes. I have just finished a perusal of the article, which was indeed rather exciting, since in nearly every paragraph I found an anticipation of some theory or observation of my own, which I had theretofore believed to be original. In fact, any one reading the article and afterwards reading The Evolution of Bird-song, would think that I had borrowed without acknowledgment a good many ideas thrown out by Mr. Samuel N. Rhoads, the writer of the essay in question. However, I am able to prove that in 1888 I had already made investigations on exactly the same lines as Mr. Rhoads, and had recorded the results of them in writing. In the summer of 1887 I began to make systematic records of the imitations I heard from imitative wild British birds, and in the course of this study various themes were attacked, such as "the influence of combat," "the influence of the love-call," "family-voices," and "the influence of imitation," etc. I wrote essays on these themes and sent them to the late Professor Harker, F. L. S. and some of them to Mr. S. S. Buckman (now an eminent geologist), with whom I had many conversations on the subjects in question. In 1890 these observations appeared, in a highly condensed form, in The Zoologist, in two papers entitled "The evolution of bird-song," and published respectively in July and August of that year. I had then of course no idea that my seemingly daring suggestions that mimicry had attuned the cries of birds to their environment, had been confirmed or anticipated in America by a writer who, whatever may be the value of his deductions, is obviously an acute observer. My papers in The Zoologist were severely handled last year by a writer who certainly had never heard of Mr. Rhoads' article; and this year the same writer, in favorably criticising in Nature my new book, employed a few congratulatory words upon my having allowed certain of my former conclusions to drop into the background. Although Mr. Rhoads and I were working on the same track, he will I am sure allow that I have gone into the subjects in much greater detail than would be possible within the limits of an article, unless it occupied the whole of the magazine in which it appeared. Mr. Rhoads traces the origin of certain tones to noises produced by the elements, such as the bubbling of air through mud, the murmurs of streams, the sibilant sounds caused by branches being rubbed against each other by the wind, the cries of the victims of predacious birds, the croakings of amphibians, and the moaning of wind in hollow trees; and I adopted the same position, though quoting different instances, in relation to each of these features. He touches on heredity, in a way that would suggest the working-out of the theme in much the same way as I have attempted to do it. In his suggestion of the original use of the voice in "hissing or choking sounds," and in my surmise that the voice was " evolved from a toneless puffing indicative of anger, or from snorts or grunts accidentally caused," in support of which idea some pertinent evidence may be adduced, we have both, I think, advanced somewhat from Darwin's proposition that involuntary and purposeless contractions of the muscles of the chest and glottis, due to excitement of the sensorium, first gave rise to the emission of vocal sounds (Expression of the Emotions, pp. 83, 84). In order to show, however, that I have not been limited to only those themes which Mr. Rhoads treats in so terse and yet so attractive a style, I would mention merely the "contents" of one of my chapters, in which some side-issues are dealt with, as follows: "Songs are generally uttered by males: exceptions-Not until birds have attained full size: exceptions-Most frequently at morning and evening influence of weather-Tendency to rise in pitch with vehemence-Only small birds properly sing-Singers arboreal birds generally-Effect of living amid foliage: on size, hearing, and voice-Accent in songs-Singers clad in sober hues-Devel opment of the eyes in detecting danger-Necessity of leisure— Labours of parent-birds-Laborious and stealthy birds habitually poor in song-Flight in song: for purposes of display-Fluttering of wings a means of address-Ventriloquism-Singing in chorus.” The study of bird-song, on the lines indicated by Mr. Rhoads and myself, is so new and so delightful a pursuit that I hasten to ask readers of THE AMERICAN NATURALIST to peruse his paper once more; for it is in America, so richly blessed with birds, that such investigations can be most easily developed, and that they promise the most accurate and helpful results.-CHARLES A. WITCHell. A Note on Dr. Herbert Nichols' Paper (Amer. Nat., Sept., 1896).-Readers of Dr. Herbert Nichols' paper on my article entitled "A New Factor in Evolution" will understand that its intemperate spirit should rule out all reply. I may say, however, that Dr. Nichol's "home thrusts" are all directed at my view of pleasure and pain, which he considers, quite mistakenly, the point of my paper. On the contrary the "factor" is entirely the influence of the individual's adaptations on the course of evolution; not at all the particular way in which the individual makes its adaptations. I took pains to reiterate. this distinction in the paper, saying (AMER. NAT., 1896, p. 542-3) "So far we have been dealing exclusively with facts without prejudicing the statement of fact at all, we may inquire into the actual working of the organism in making its adaptations. Before taking this up, I must repeat with emphasis that the position taken in the foregoing pages, which simply makes the fact of ontogenetic adaptation a factor in (race) development, is not involved in the solution of the farther question as to how the adaptations are secured." So I see absolutely no point in Dr. Nichols' criticisms. The other question, which involves pleasure and pain, is discussed in the latter part of my paper; but it is not that, but my book which Dr. Nichols attacks with the grossest misunderstanding. I do not at all believe the main things which he attributes to me; first, the position that there are no pain nerves, and second, that there is a "psychic factor" which is an "efficient cause" in evolution. Psychologists know Dr. Nichols' hobby and allow for his intemperateness. J. MARK BALDWIN. Princeton, Sept. 25, 1896. MICROSCOPY.' Methylen Blue.-A few points observed in the use of Erlich's methylen blue method by the investigators in the Marine Biological Laboratory at Woods Holl, Mass. may be of general interest. This method has been successfully applied during the past summer to the study of the nervous system in a great variety of forms including vertebrates, crustacea, annelids, echinoderms and tunicates. Ehrlich's intra vitam methylen blue prepared by Grübler was used for staining the nerve tissues. The stain was applied by injecting a 1- per cent solution of the methylen blue made in normal salt solution, into the blood vessels, body cavity or lymph spaces or by immersing small animals or excised pieces of nerve tissue in a weak solution. The method of application and strength of the solution were determined by experiment for each animal and tissue. During the action of the stain, the animal or tissue was kept as nearly as possible in its normal condition. Everything seems to depend on keeping the tissue alive, and in bringing the stain in contact with it in a solution of a strength suitable for obtaining the best results. The abundant supply of oxygen to the staining tissue was of great importance in some cases, while in others it seemed to make little difference. It was found, as suggested by Dr. C. Huber, that animals which live in the dark, stain better in the dark than in the light. The relaxation of the tissues by the use of chloroform or chloral hydrate seemed to be more favorable for the staining of some elements of the nervous system, while others did not stain which stained in the unchloroformed animal. It was found that recently caught and perfectly normal animals stained more satisfactorily than those which had been kept in confinement for some time, unless under very favorable conditions. In the case of the dogfish, active animals were killed by decapitation. The stain was applied by injecting a 1-1 per cent solution of the methylen blue into the blood vessels for the central nervous system and by immersing small pieces of nerve tissue in a weak solution of the stain for the sense organs. The length of time required for the intra vitam staining varied widely, annelids requiring 4-5 hours, while dogfish only require 1hours, either by injection or by immersing the tissue in the stain. 1Edited by C. O. Whitman, University of Chicago. When small transparent pieces of tissue were to be examined, they were fixed in a saturated solution of picrate of ammonia in distilled water from 2-4 hours and were then mounted in a mixture of equal parts of pure glycerine and distilled water to which a small quantity of picrate of ammonia is added. When opaque or large pieces were fixed in this way they were sectioned by the freezing method. After fixing in the picrate of ammonia, the tissue was placed in a saturated solution of sugar for one hour and was then transferred to a piece of blotting paper to remove the syrup from its surface. It was then placed in a thick solution of gum arabic for fifteen minutes and then transferred to the plate of the freezing microtome where it was frozen by means of liquid carbonic acid. The sections were mounted in dilute glycerine as in the other case. The principal advantage of this method is its rapidity, but neither serial sections nor those of equal thickness can be obtained. In order to obtain serial sections by the paraffine method, the tissues were fixed in Berthe's Fluid.2 For vertebrates: For invertebrates: Molybdate of ammonia, 1 gram. Distilled water, 10 c. c. Hydrochloric acid, 1 drop. Peroxide of Hydrogen, 1 c. c. A different formula is used for tissues of invertebrates as less oxygen is required than for vertebrates. The fixing fluid must be cooled on ice before placing the tissue in it. After remaining in the cold fixing fluid for from 2-4 hours the tissue is thoroughly washed with cold water which generally takes about two hours although it has been continued for twelve hours without injury. It is necessary to remove all the molybdate of ammonia by thorough washing if permanent preparations are to be secured. The tissue is then passed rapidly, ten to fifteen minutes in each, through the ordinary grades of alcohol to absolute, all being kept cold with ice. The tissue should be left in the absolute alcohol for about two hours at a freezing temperature and the alcohol be changed several times. The stain is dissolved by dilute alcohol at ordinary temperatures. Dr. Huber's plan of placing the tissue directly in cold absolute alcohol on removing it from the water and changing several times for a period of two hours, gave good results. 2 Archiv. f. Mikros., Anat. Bd. 44, Heft 4. |