The Structure and Function of the Mammalian Heart.-Report of the Committee, consisting of Professor E. A. SCHÄFER (Chairman), Mr. A. F. STANLEY KENT (Secretary), and Professor C. S. SHERRINGTON. (Drawn up by the Secretary.) The research may be divided into three parts: 1. Observations on the Structure of the Heart. 2. Experiments on the Relation between Structure and Function. 3. Experiments with Anæsthetics. 1. Observations on the Structure of the Heart.-These observations have been made principally on human hearts, and tend to show that the condition which I have described' in the hearts of animals lower in the scale persists even in man. That is to say, the auricles and ventricles are connected by strands of muscular tissue passing across the groove, though, as might be expected from my former observations, these strands are less marked in man than in the lower animals. In man, as in all other animals examined, the muscular connection is more perfect in the young condition, and the younger the subject the more perfect the connection. To go more into detail, the ring at the base of the auriculo-ventricular valves is composed of a dense mass of white fibrous tissue in which are scattered many connective-tissue corpuscles, and this mass becomes continuous with the connective tissue running between the muscular fibres of auricle and ventricle respectively. The greatest development of connective tissue takes place at the bases of the valves, which are supported on specially thickened portions of the ring, and are largely composed of bundles of fibres running out from it. Bundles of muscular tissue also occur in the valves, and these bundles. are usually connected directly with the muscle forming the walls of the auricle. In actual shape and arrangement the fibrous tissue forming the ring differs in different situations. At the posterior aspect of the left ventricle the auricular muscle is completely separated from that of the ventricle by a more or less pyramidal mass of connective tissue, the base of the pyramid being directed outwards and forming part of the external surface of the heart, the apex being directed inwards and becoming continuous with the base of the mitral valve. The auricular muscle runs downwards on the inner aspect of this mass of fibrous tissue, and ends as a thin sheet just above the base of the valve. The ventricular muscle ends as a much thicker mass just beneath the base of the valve. An exhaustive examination has been made of the relations of muscle and connective tissue in this situation, but a description without figures would be tedious, and followed only with difficulty. Suffice it to say that in the human heart, as in the hearts of other animals, the auricles and ventricles are connected by muscular tissue, and their connection is the more perfect the younger the heart. 2 and 3. Experiments on the Relation of Structure to Function and 'Journal of Physiology, XIV., i and 5. Experiments with Anaesthetics. It will, perhaps, be best to take these two sets of experiments together. Shortly summarised, they have been made with the object of determining how the above-described points of structure affect the working of the heart, and more especially what practical use can be made of the knowledge gained in these observations. It is well known that in young animals it is exceedingly difficult to produce any effect by means of chloroform-in fact, in my experiments I have often found it almost impossible to anæsthetise animals only a few days old. Gradually, as age increases, they become less refractory, and at a few weeks old (in the case of kittens) chloroform produces the same effects as in the adult. More than this, however, in the newly-born animal it is almost impossible, push the anaesthetic as you will, to produce stoppage of the heart, though this is one of the accidents most to be feared in administering chloroform to an adult animal. But even in the adult, if the thorax be opened and the heart examined immediately after death by chloroform poisoning, it will be found that, though the heart as a whole is quiescent, a portion of it, the right auricle, is still beating. In other words, it is not the initial stage of the beat which is absent; the quiescence of the heart is rather due to a failure in the transference of the beat already initiated from auricle to ventricle. This failure occurs only in the adult or nearly adult heart, and it has been shown that it is precisely in these adult or nearly adult hearts in which the connecting link between auricle and ventricle is reduced to a minimum. The failure of the heart's action, then, may be supposed to be due to the failure of a strand muscle of comparatively small sectional area to convey to the ventricle a wave of contraction started in the auricle. It occurred to me, then, that it might be possible in cases of chloroform poisoning to so improve the conducting power of this strand of muscle as to enable the waves of contraction to once again pass over the junction and cause contractions of the ventricle. My experiments upon this point are at present incomplete, but I have obtained results which lead me to hope that the research will not be entirely without practical results. On recent Researches in the Infra-red Spectrum. [PLATES II-IV.] [Ordered by the General Committee to be printed in extenso.] I PRESENTED to the Association in 1882 at Southampton an account of some researches made by means of the bolometer in the infra-red spectrum formed by a glass prism; but though these labours have continued with occasional intermission during the past twelve years, it is, for reasons which will be explained later, only within the past three years that any notable advance has been made, and only within the past twelvemonth that such a measure of success has been attained as justifies the present communication. This is not the time to give any historical account of discovery in the infra-red spectrum, but all those interested in the subject know that the 1894. HH first investigator here was Sir William Herschel, whose observations consisted essentially in finding that there was something which the eye could not see in a region which he proposed to call the 'thermometric spectrum.' His distinguished son, Sir John, made a curious anticipation of later. discovery, by indicating, though crudely, that this invisible heat was not uniformly distributed, and a similar conclusion was reached in an entirely different manner, through the thermopile, by the too-early-lost Melloni. So ignorant, in spite of these investigations, of those of the elder Draper, and of the elder Becquerel, were we till lately, that when, quite within my own recollection and that of most of you, Lamansky in 1871 published from his observations with the thermopile a crude little illustration showing three inequalities in the energy curve, universal attention was excited by it among those interested in the subject. Among other minds, my own then received a stimulus which turned in this direction, and having, as it seemed to me, exhausted the capacities of the thermopile, I invented an instrument for continuing the research, which was afterwards called the bolometer, and with which in 1881, at an altitude of 13,000 feet upon Mount Whitney, I found spectral regions hitherto unreached, and whose existence had not been suspected. I returned with a strong impression of the prospective importance of this discovery, and laboured at the Alleghany Observatory in improving all portions of the new method of research, especially of the bolometer and its adjuncts, with the twofold object of obtaining greater sensitiveness to heat, and greater precision in fixing the exact point in the spectrum where the change of heat originated. With the former object such a degree of sensitiveness was at that time reached, that the bolometer indicated a change of temperature of 1000 of a degree Centigrade, and with the latter, such precision, that it was possible to fix the relative position of a line not merely with a possible error of a considerable fraction of a degree, such as Lamansky's determination is evidently subject to, but with a certainty that the error would be within a minute of arc. The range of the apparatus in wave-lengths was almost unlimited as compared with any other process, and both its sensitiveness and its possible precision seemed to be at that time notable as compared with previous methods, for a great advance was made on anything done before with the thermopile, when the presence of the well-known 'D' line of sodium was rendered sensible (though barely sensible) even as a single line by the change of temperature. This sensitiveness was also, as has been said, accompanied with the possibility of unusual precision. The results of this labour were laid before the British Association in the communication already alluded to, and which exhibited ten or twelve inflections of the curve in the portion till then almost unknown, which extends from a wave-length of 1 to a wave-length of nearly 3", at which point the glass prism then used became wholly opaque to radiation. The positions of these inflections were fixed with a precision quite impossible to the thermopile, but this exactness was only obtained in practice by a process so slow as to be almost prohibitory; and with this apparatus I made in those earlier years such a number of observations as I hardly like to recall, so disproportionate did the labour inherent in this method seem to the final result. The justification of this labour seemed to lie in the fact that it does not appear that photography has ever rendered anything much below a wavelength of 1-anything at least which has been reproduced for publication in a way which gives confidence that we are in touch with the original. The processes which involve the use of phosphorescent substances have given some indications of lines considerably below 1", but it is safe to state that the work which has just been referred to as communicated to this Association in 1882 presents almost the only indications which we have possessed, even up to the present time, about the lower infra-red solar spectrum. Now the curve which was given, even in the later Alleghany observations, made with the rock-salt prism, contained but a dozen inflections below the wave-length of 1-5, and these inflections, with their correct prismatic and wave-length positions, represent, I think, most of our present knowledge in these regions, even to-day. To understand the method by which there were attained, but only at this great cost of labour, results till then unreached, it may be repeated that the bolometer had been rendered more sensitive than the thermopile, but that it was capable of being pointed, and its position in the spectrum being measured only by a tedious process, which has been exclusively used till lately (but which that presently to be described advantageously replaces). Whichever process is used, when the bolometer thread touches a cold line in the spectrum (since what is black to the eye is cold to it), a larger current flows through the galvanometer, and the spot of light marking the needle's motion is deflected through a certain number of degrees. From this point forward, the new process, whose results I am about to have the pleasure of bringing before you, differs widely from the old. In the old, two observers at least are engaged one, who notes that reading of the micrometer or of the vernier, which fixes in angular measure the exact part of the spectral region whence (though nothing is visible) a thermo-electric disturbance has proceeded; and another, who simultaneously notes through how many divisions of the scale the spot of light from the galvanometer mirror is deflected by the same electric disturbance. The process may be compared to a groping in the dark, and it was only by these means that the considerable inflections of the energy curve much below the region about 1 were then fixed by the bolometer, by being gone over again and again with what seemed almost interminable repetition, and which did in fact call for over a thousand galvanometer readings to obtain the position and amount of each single inflection of the energy curve, with the degree of accuracy which was then obtained, and which was shown in the former memoir. If it took two years to fix the position of twenty lines by this process, it would take two hundred years to fix two thousand, supposing they existed, and it became evident that if the bolometer continued to be the only means available, new and more effective methods of using it must be found. New Methods. About ten years ago a plan was first studied, which has ever since been maturing, by means of which this work could be carried on, not only with far greater rapidity, but with greater certainty, and by an automatic process. The idea in its original simplicity is very easily understood. In the old process, just described, the deflection of a spot of light upon a scale was read by one observer, while another read simultaneously the position in the spectrum of the cold band, or line, which caused the thermoelectric disturbance. Now, in imagination, let us take away both the observer at the circle and the one at the galvanometer, and in the latter case remove the scale also, and put in its stead a photographically sensitive plate. As the needle swings to the right or left the spot of light will trace upon the plate a black horizontal line whose length will show how far the needle moves and how great the heat is which originated the impulse. If this be all, when under an impulse originated by the movement of the spectrum over the bolometer thread the needle swings a second time, it will go over the same place; but if the plate have a uniform vertical movement, proportional to the horizontal movement of the spectrum, the combination of the two motions of the needle and the plate will write upon the latter a sinuous curve which will be, in theory at least, the same as the curve formerly deducible, only with such pains, from thousands of such galvanometer readings. If we suppose that the movements of the invisible spectrum are controlled by clockwork, so that this spectrum is caused to move uniformly over the bolometer thread, and that these movements are, by accurate mechanism, rendered absolutely synchronous with those of the moving plate, it is clear that we shall be able to readily deduce from the photographic curve traced on the latter not merely the amount of the heat, but each particular position in the spectrum of the thread of the bolometer, which alone can correspond with any given inflection of the curve. Thus simple is the theory, but no one had better occasion to know how difficult the practice would be than myself. The researches by the old method and the early attempts to improve them were interrupted by my acceptance, in 1887, of a position which implies the administrative charge of different branches of the public scientific service, and of duties largely incompatible with original research. What time could be spared from these was, however, partly employed in elaborating the plan of investigation just referred to. An appropriation had been asked of Government for the establishment, on a modest scale, of an Astro-physical Observatory in Washington, whose first work should be the investigation of the whole infra-red solar spectrum, by some means which would open that great region to knowledge. It had been asked of Government, because it seemed that such knowledge, if attained, might teach us facts about the sun and the absorption of its rays by the terrestrial atmosphere, which, there was ground to hope, would ultimately lead to results of such importance as to justify this national aid. These observations were resumed in 1890, on the new system, with the aid of the Smithsonian Institution. which provided larger and more efficient apparatus, whose design embodied the results of nearly fifteen years' study of these subjects. Pending the provision of a suitable observatory building, an inadequate and temporary one was erected in the Smithsonian Park in Washington, to shelter the apparatus presently to be mentioned, with which it was designed to commence work, while making provision for more permanent scientific quarters-which, I may add, are still lacking. Apparatus. The Foucault Siderostat -perhaps the most powerful instrument of the kind existing-was originally made by Sir Howard Grubb of Dublin, from my indications; but its dispositions have since been considerably modified. A beam from its twenty-inch mirror is conveyed through the slit of a horizontal collimating telescope having a rock-salt objective of nearly seven |