failure.

Let this be so; it is no argument. Even Alexander's little world was not conquered in a day. No matter the magnitude of the whole, each part apprehended is a gain to human knowledge and somewhere has its practical application; part by part, every portion fixed upon the student's mind makes of him one better prepared to work out further problems for himself and for the rest of us. Nor am I unaware of the fact that these principles are here and there at the present time being given in one or another of the existing branches of medical study; but a part here and another there are by no means the same as a careful and definite resume of the science and its scope of application to our needs; and further, those branches now working out these problems as from time to time needed in elucidation of their own difficulties are in so far doing preparatory work from which there is every reason to excuse them if we would wish them their fullest development in a speedier time. The ophthalmologist before his class goes over a course explanatory of the physics of light and lenses; the microscopist prefaces his instruction by a somewhat similar outline; the aurist discusses the vibrations of air and solids in the transmission and development of sound; the physiologist the diffusion of gases, the laws of osmosis, questions of hydrostatics and hydrodynamics and practically every other subject pertaining to the branch in the explanation of a great number of instruments of precision and in elucidating that which is known and conjectured as to the various bodily functions; the obstetrician the resultants of forces applied variously, successively and co-ordinately in directing and accomplishing the birth of the child-in short, each instructor takes up before his class some part or parts of a subject of fundamental importance to all and deserving an individual and dignified position in the scheme of instruction, and each loses just so much of his time and opportunities to press a little further toward his assigned object in the general plan.

What would I make of physics in the medical curriculum? To the writer's mind the branch has a direct and particular phase of application which is spoken of as medical physics. For the stu

dent who has had training in the subject when admitted to the medical school I would insist upon a course of lectures or text-book study with actual demonstration covering the general principles, and for all students laboratory exercises designed to familiarize them with the principles and actual manipulation of the various instruments used in experimental and in practical medicine and to illustrate by experiment and attempts to mechanically reproduce outside the body by simple models such phases of nature's operations as may thus be copied. The latter part of the scheme, the distinctively medical physics, should be further elaborated according to the wish and ability of the instructor, by lecture or other mode of explanation, in indicating the multiplicity of factors and their mutual relations in the accomplishment of bodily functions, and with immediate and direct reference to the influence of modification or loss of any factor toward the development of disease and its symptoms.

The matter of the construction and mode of handling of the various instruments used in experimental and practical medicine needs no explanation or illustration of its value to the student; and the release of the instructor from the necessity of discussing fundamental principles involved in his branch will doubtless be accepted as affording more chance for increased attention to and development of the particular features of his special subject. Dealing with those students who have attained the general ideas and a fair technique, the physiologist, the pathologist and particularly the clinical physician and surgeon or obstetrician have fair field for presenting the final problems of their branches, the ultimate objects of instruction. There is no part of the course of medical education free from such problems; but I may choose several for the sake of illustration which occur as I write.

The student is taught that glandular secretion or excretion is dependent on the presence in the gland of more or less freely circulating blood as the source of the particular substances elaborated by the gland. He witnesses a case of acute renal suppression in the hospital ward and later at the autopsy meets with a deeply con

gested, red and swollen kidney. Will it help his appreciation of the development of the symptoms if his thoughts be directed along some such line as follows? Setting aside for the time, but in no way denying the importance of selective cellular activity, the physical forces and methods involved in urinary excretion are brought forward in greater prominence. The structure of the kidney speaks for filtration as at least one factor in renal activity, filtration of the fluid and more or less of the urinary salines from the blood. For the example in hand it is immaterial what further action the epithelium of the convoluted tubules may accomplish. One may well compare the renal unit (the malpighian tuft and its enveloping capsule and the tube leading therefrom) to a separator funnel lined with a permeable membrane and fitted with a compressible discharge tube. My meaning may, perhaps, be more readily apprehended by reference to the diagram (Fig. 1) in which is represented an ordinary separating funnel, within which, separated by an appreciable space from the inner surface of the funnel is fitted. a permeable and expansile membranous sac (a), provided with an entrance tube (b) and exit tube (c), both of the same expansile type as the sac itself, and the exit tube (c) coiled about the compressible discharge tube (d) of the funnel. In a rude way this follows the type of the coiled capillary tuft within Bowman's capsule and the arrangement of its emergent capillary about the convoluted tubule of the kidney. Presuming that the pressure of the fluid within the membranous sac in the funnel (capillary tuft within Bowman's capsule in the kidney) is marked but insufficient to stretch the sac to close adaptation to the wall of the funnel the contained fluid will escape through every part of the membrane into the space between the sac and the funnel; and if that pressure be lowered the filtration of fluid will be disminished in rate. On the other hand, if the pressure within the sac is increased (increase of vascular tension in the renal vessels as in marked congestion), it follows that the sac must expand to become closely applied to the wall of the funnel (the tuft to the wall of Bowman's capsule); whence it is clear that there is opposition to the escape of the fluid

from the sac save at the limited surface opposite the opening of the discharge tube of the funnel (the beginning of the proximal convoluted tubule of the kidney). It is to be realized that increased pressure within the sac must be carried forward along its emerging tube (c), leading to the distension of the latter (providing the same difficulties of discharge as in the tortuous renal capillaries and veins), in this connection the particular feature of its expansion referring to its encirclement of the discharge tube of the funnel (the plexus of emerging capillaries about the convoluted tubules and the general capillary distension within the renal mass) If room for such distension is not given save at the expense of the caliber of the encircled discharge tube (as is the case in the kidney from the pressure of the general renal tissue and the resistant renal capsule) there must result narrowing or possibly closure of the discharge tube, affording another mechanical factor in inhibiting whatever tendency toward filtration may continue in the funnel above; and if the pressure be sufficient through these two obstructions one may readily infer total suppression of the filtration proThe walls of the capillaries of the malpighian tuft are by no means entirely comparable to ordinary porous filtration membranes, but in the relation here proposed are at least analogous and in illustration of the mechanical influences named will easily bear comparison; and silence concerning any part played by the renal epithelium in no wise impairs the illustration. Nor is it difficult to fix in the same bit of apparatus the ideas of the student as to the relation of urinary suppression and hæmaturia in such cases of renal stagnation from congestion.

cess.

Another striking example from pathology suggested by the same line of thought concerns the explanation of the posture assumed by the patient with broken cardiac compensation and approaching his end. It is invariable that as the heart fails the individual finds himself little by little forsaking his natural low recumbent posture at rest, seeking a higher and higher pillow, and as death approaches finding comfort only in a sitting posture, with the limbs more or less elevated; and invariably change from this position

to a lower or higher (more erect) attitude calls forth evidences of special cardiac effort. There are here of course, as in most cases, a number of factors to be considered for the full explanation of the whole symptom picture; but of these that of the influence of gravity in distribution of the blood is the element of variation to which mainly must be attributed the symptoms in question. One should realize here that in the erect or sitting posture the column of blood in the aorta and its branches beyond the turn of the aortic arch must by its weight naturally produce no immaterial tendency toward keeping up the usual downward current (other factors of aid and resistance being disregarded for the time for the sake of the argument; while in the recumbent position the distribution of the blood over the whole body is practically the result of the propulsive force of the heart and vessel walls alone. The difference in cardiac labor in these two postures may be roughly stated as the difference in lifting the column of blood from the left ventricle to the turn of the aortic arch and to the head in the first instance and the lateral propulsion of the whole arterial blood mass in the second. Or, to use a homely simile, it is comparable to throwing a ton of coals, shovelful by shovelful, over a fence and allowing it to fall fifty feet in a vertical direction in one case, and in the second instance to the labor of transporting the same coals, shovelful by shovelful, across a level space for fifty feet and depositing it in a new heap. With such a view it is easily realizable that there is more labor demanded of the heart with the body adjusted in recumbent position than in either the erect or in the sitting posture, and that when the circulation is from many influences already weak and feeble, the added strain upon its walls may well call out marked evidences of its exertions. The sitting posture is assumed rather than the upright in such an instance for easily stated reasons, namely, the usual general muscular enfeeblement of the individual and (in the absence in either position of chance for free muscular and respiratory aid in venous return) the less labor of lifting the venous column of blood through the shorter vertical from the feet to the right heart when the individual is sitting than when stand