COLUMBIA LIBRARIES OFFSITE HEAITH SCIt NCI S SI ANIlAMD HX64171990 QP55 .G98 Contributions to pra RECAP CONTRIBUTIONS TO PRACTICAL PHYSIOLOGY AND PHARMACOLOGY BY CHARLES CLAUDE GUTHRI^ Professor of Physiology and Pharmacology University of Pittsburgh Medical School 1915 College of ^fjpgicianj; anb burgeons Hibrarp Digitized by tine Internet Archive in 2010 witii funding from Open Knowledge Commons (for the Medical Heritage Library project) http://www.archive.org/details/contributionstopOOguth CONTRIBUTIONS TO PRACTICAL PHYSIOLOGY AND PHARMACOLOGY BY CHARLES CLAUDE GUTHRIE Professor of Physiology and Pharmacology University of Pittsburgh Medical School 1915 QP6'5 Published and Presented by THE WRITER CD in CTJ ^ CONTENTS Page Myograpli 7 Bath 12 Muscle Volume Tiilie 15 Weights 15 Ergograph 17 Gas Chamber Electrodes 17 Thermal Electrodes 20 Cardiograph 22 Simple Electrodes 25 Special Cardiograph 26 Frog Holder. Form 1 27 Frog Holder. Form H 27 Frog Holder. Form III 2S Turtle Holder rso Tuning Fork ;!1 Signal. Form 1 154 Signal. Form II 35 Drum Key for Use in Primarj' Circuit 36 Combined Rheocord and Bridge. Form 1 39 Combined Rheocord and Bridge. Form II 42 Combined Primary Key and Secondary Cut-out Key, Switch and Com- mutator 43 Combined Constant Contact Primary and Automatic Secondary Cut-out keys. Form 1 45 Combined Constant Contact Primary and Automatic Secondary Cut-out . Keys. Form II 46 Combined Constant Contact Primary and Automatic Secondary Cut-'out Keys. Form II 47 Multiple Drum Stand 47 Automatic Myograph Key 49 Drum Contro Standi Form 1 51 Drum Control Stand. Form II 54 Recording Drum and Controller 55 Combined Primary and Secondary Circuit Controller 64 Combined Coil, Current Controller, Rheocord, Primary and Secondary Keys, Switch and Commutator (Combined Coil and Current Controllers) 68 INTRODUCTION As all nrc aware of the limited amount of time provided for Physi- olog'v and Pharmacology in the modern medical course, and also, of the nature and aims of such courses, it is unnecessary to give lengthy rea- sons for the view that time-saving laboratory methods are desirable. By providing the student with simple, efficient and sturdy appa- ratus designed especially to meet the requirements of the courses, I l)elieve much time now devoted to the purely mechanical side of the experimental work may be saved, thereby enabling him to perform more experiments in the allotted time. Also, his results will be more certain and accurate, and being less burdened with mechanical details, his mind will be freer to contemplate the physiological or pharmaco- logical phenomena revealed during the time of the experiment, a j)oint I would strongly emphasize. Finally, I believe that under such condi- tions the courses would have larger pedagogic values. The view has been held that by assembling, adapting and devising all of the separate pieces of apparatus for each experiment the student gains valuable practical training, both manual and technical. I believe the value of this feature of such courses has been overestimated in the past ; and with modern preliminary requirements for medical students, I see no reason why the Physiologist or Pharmacologist should deem it a part of his duty to teach manual training or elementary physics. Only a very small percentage of such students become teachers or investi- gators in these fields, and the course with time-saving apparatus is not less stimulating — in fact, it is more so. From a purely technical standpoint, physiology' has not kept abreast of her sister science physics, save in certain special fields. Even in muscle-nerve physiology there is no uniformity of methods in different laboratories. In general, the student is obliged to adapt apparatus to particular ends. Therefore, results are secured at the expense of much time, and the results themselves are prone to be inaccurate. The mechanical errors are great and imperfectly known, since for the most part such apparatus is not standardized. Also, time and the limita- tions of the apparatus render study of the finer and more ultimate phenomena impracticable. Pedagogically, for the time expended, the result is unsatisfactory. I believe that much can be done to remedy the condition, both by individual teachers and by co-operation between schools. The material presented in the succeeding pages is offered from this standpoint. Though the task has been very time-consuming, the improvement in the students' results and the very marked extension of the experimental work rendered possible in the laboratory is abundant justification. I shall be glad if others can in any way profit by it. All of the apparatus has been thoroughly tested, both directly for mechanical faults and by use in experiments for which it is designed. Much of it has been used as regular student equipment for one or more terms, which is, perhaps, the severest test to which apparatus is sub- jected. In designing and constructing, the purposes and conditions of its use have been primary considerations. Simplicity and durability of design have been retained at the expense of accuracy when the difTer- ence in the latter has been largely of theoretical importance. Absolute perfection is desirable, but difficult of achievement, even in the most highly specialized instruments and to have striven for this at the expense of simplicity, durability and cost would have conflicted with the plan under which the work was undertaken. Therefore, although recognizing its imperfections, I am convinced that when used for the purposes for which it is designed, the apparatus gives credible results which, from a practical standpoint, are satisfactory. The probable errors and practical limitations are given in most cases along with the descriptions. It is planned for the second number of this contribution to deal with the working directions based upon laboratory experience with the apparatus. The value of such directions is enhanced by their actual employment in the laboratory and for this reason they may not be printed until they have been further tried out in the regular course dur- ing the approaching session. I shall welcome suggestions both in the way of criticisms and in the way of improvement of the apparatus. The drawings reproduced were made to scale so that with the descriptions and specifications any competent mechanic can construct the apparatus. It is a great pleasure to acknowledge the helpful suggestions of past and present members of the departmental stafif and particularly the painstaking work of Mr. Robert Tontrup, mechanician, and the patient and skillful testing and drawing of Miss ]\Iarian Lee, research assistant. Private publication was decided upon owing to the policy of appro- priate journals of barring or restricting purely technical material. It seemed most desirable to publish all of the material at one time and in one place. July 31, 1915. CONTRIBUTIONS TO PRACTICAL PHYSIOLOGY AND PHARMACOLOGY PART I— APPARATUS ^Myograph This form of myograph is designed primarily for recording con- tractions in isolated skeletal, cardiac and plain muscle, but it is also convenient and efficient for studying muscle in situ, Figs. 1, 2, and 3. Fig. 1. ^Myograph assembled with drum stand, automatic stimulating key and rheocord, hand primary key and secondary cut-out key and switcii, coil, and battery. It has but slight inertia. The frame is of brass. It is pierced by holes and threaded sockets for various attachments. The lever may be used as a simple lever with both arms horizontal or as a right angle lever, 8 Myograph the recording arm being horizontal and a short arm to which the force is appHed, perpendicular. The lever is made of thin brass tubing rigidly attached at the fulcrum, Fig 4. This point is transversely pierced with a tube which firmly holds the axle which turns in bearings in the frame. The entire construction is such that, though light, the instrument is very rigid and compact. All parts are readily accessible. The horizontal arms of the lever are pierced with perpendicular holes at intervals of one centimeter from the fulcrum. These holes serve to mark centimeter intervals, and as points of attachment for the QU: Fig. 2. Myograph. Posterio-lateral view. A. Frame. B. Lever. C. lyever rest or after-loading screw. D. Anterior support rod. E. Detachable support rod. A side socket for E is shown in the frame. F. Nerve electrodes. G. Insulating sleeve. The method of mounting a muscle-nerve preparation is shown by the dotted lines. weight pan and other accessories. The openings in both ends are taper reamed to facilitate attachment of extensions. The forward arm to which the writing point is usually affixed is transversely pierced about two centimeters from the end by a pin which is permanently soldered in place, so that when a straw is forcibly thrust into the tube it is split, and thus expanded ; or if the end be cut obliquely, it is compressed firmly between the pin and the side of the tube, thus providing a simple means of instantly and rigidly affixing straws of various sizes. MyOGKAI'H The perpendicular arm is a tube \v1ik1i forms a spring socket into which extensions are thrust. These extensions are of various lengths; Fig. 3. Myograph. Anterio-lateral projection. they consist of a brass tube into one end of which a solid metallic point is fixed. The point serves to attach one end of the muscle to the lever by transfixing it. A collar on the point serves as a stop to the tissue, and its lower surface is at a known distance from the fulcrum, usually Fig. 4. Details of construction of lever, tissue points, and attachments of anterior sup- port rod to frame and insulation. 10 Myograph three to five centimeters, depending upon the length of the extensions employed. Backward excursion of the arm is limited by an adjustable stop or rest screw which pierces the posterior wall of the frame. A fixed support for the other end of the muscle is carried on a horizontal rod which is firmly attached to the anterior surface of the frame. It consists of. a spring socket similar to that of the perpendicu- lar lever arm into which are inserted similar pointed extensions. The point of the socket on the horizontal support rod is adjustable by means of a set screw conveniently placed, thus permitting adjustment for tissue preparations of different lengths. The extension is of such length that the lower surface of the collar, which acts as a stop to the tissue, is somewhat above the horizontal plane of the stop on the per- pendicular lever arm extension, so that the muscle contracts more nearly in the line of the circumference of the arc described by the perpendicular arm, i. e., not tangentially. Fig. 5. Thus the movement Fig. 5. Diagram to show the relation of the direction of the pull of a muscle to the arc of the perpendicular myograph lever. F. Fulcrum. P. Horizontal plane of movable point stop. P'. Horizontal plane of fixed point stop. A. Arc of perpendicular lever. M. and M'. Longitudinal axis of muscle. of the lever is more nearly uniform throughout the contraction. The extensions serve not only as tissue holders but as electrodes for direct stimulation of the tissue. They may be easily withdrawn from the spring sockets and replaced by others of different lengths. The adjust- able socket for the fixed arm may be removed from the support rod. The anterior support rod is immediately below and parallel to the forward arm of the lever. It is electrically insulated from the frame, Myockai'ii 11 aiul the forward ciul is providctl with a hole for the i)Ur])Osc of making electrical connection in order to lead a current to the muscle through the fixed muscle point and electrode. Electrical connection to the mov- able muscle point and electrode is made by inserting the end of the wire conveying the current into a tube provided for the purpose, Fig. 2, H. No other form of binding post is used, as they are more cumber- some, more prone to get out of order, as through loss of parts, and they are no more effective than the form described. Besides, this method of connecting is time saving. A nerve electrode holder for adjustable electrodes is attached to the far side of the frame, Fig. 2, F, and Fig 6. The body of the holder is of fibre and, therefore, insulates the electrodes from the myograph Fig. 6. Myograph nerve electrodes, electrical connections. Details of construction and method of making frame. The electrodes consist of brass tubing, into the lower ends of wdiich are fitted metallic points which are curved to support a nerve or other tissue laid upon them. The holes in the upper ends of the tubes of the electrodes serve for making electrical contact. The spring sockets of the holder into which they fit permit of their instantaneous removal or adjustment. The support rod attached to the anterior surface of the frame and which carries the fixed point serves in many experiments as a support for the myograph, as it may be clamped to a stand rod without inter- fering in any way with the action or manipulation of the myograph, Fig. 1. In addition, the posterior and far sides of the frame are pro- vided with threaded sockets into which a detachable support rod may be fastened as occasion indicates. The support rod is provided with a fiber collar so that it may be electrically insulated from the clamp. The 12 Bath collar is three centimeters long ; it is split longitudinally through one side so that it may be easily adjusted to any point upon the rod or re- moved therefrom. It may also be used upon the support rod attached to the anterior surface of the frame. The support rod may be quickly removed by unscrewing from the frame ; if tight it may be loosened by using an ordinary clamp as a wrench. In addition, it is pierced trans- versely near its posterior extremity by a hole through which a pin such as a nail may be thrust to facilitate its adjustment or removal. When the rod is screwed into the far side of the frame it is then fixed at right angles to the direction of the lever. This arrangement is very con- venient as in recording the contraction of a frog's heart in situ. Various accessory attachments greatly extend the use and value of the myograph, and, therefore, will be described in detail. Bath As a ready and simple means of applying solutions to isolated tissues, the adjustable bath is used, Fig. 7, A, and Fig. 1. The dish Fig. 7. A. Myograph bath holder and dish. B. Modified form of dish requiring but S to 8 cc. of liquid to submerge tissue. Bath 13 is of glass, circular in form. In diameter it is 52 mm. and in depth 30 mm. The walls and bottom are 1.5 mm. thick. It is firmly grasped by the spring prongs of the holder, but is instantly detachable, and, therefore, is easily cleansed. The holder is solidly and substantially Fig. 8. Tubular form of bath and holder. A. Holder mounted on myograph frame. B. Holder mounted on support rod. constructed. It consists of an open brass ring attached to a support rod and equipped with three spring fingers for holding the dish, spaced at equi-distant points of its circumference. The ring also acts as a spring owing to the fact that it is not closed. The dish is firmly held 14 Volume Tube in position so that the holder may be inverted without the dish becom- ing displaced. When inverted, /. e., when the spring prongs are directed downward, it serves as a ring support for a beaker in such experiments as require changing the temperature of the solution. The bath renders a moist chamber unnecessary in most experi- ments as all of the tissues may be instantly submerged in or removed from blood or salt solutions by simply raising or lowering the dish. The large surface of liquid exposed favors gaseous exchange between the air and liquid. The tissue may be stimulated while submerged in the bath or while exposed to the air, as desired. In the latter case, undue drying is prevented by raising the bath at intervals to submerge the tissues. A tubular form of bath and holder is shown in Fig. 8. The tissue is attached to a fixed point carried by the holder and to the posterior arm of the lever. Wire is used for attaching the tissue to the lever. After the tissue is mounted the bath tube is adjusted from below upwards and is held in place by the spring prongs. The tissue may be electrically stimulated by connecting one electrode wire to the myograph frame and the other to the bath holder. Fig. 9. Volume tube. Weights 15 The chief advantage of this method is that less liquid is required to submerge the tissue than in the regular form of dish, so it is recom- mended only in experiments where the quantity of bath liquid is re- stricted, as in the case of expensive drugs. The modified form of ordinary bath, Fig. 7, B, requires less liquid than the tubular form. The ordinary form of dish requires from about 25 to 40 cc. ; the modi- fied form 5 to 8 cc. ; and the tubular form 8 to 15 cc. of liquid. Muscle \'olume Tube A modified form of tubular bath shown in Fig. 9 serves as a muscle volume tube. Weights The weights are flat metallic rectangles measuring about 25 by 30 mms.. Fig. 10, A. A set consists of nine, weighing ten grams each, and two, weighing five grams each. Near one extremity they are pierced by a hole by means of which they may be hung on a hook sus- pended from the lever. Fig. 10, B. The hook is of such dimensions and shape that the other parts of the apparatus do not interfere with the placing or removal of the weights. Fig 11. It weighs one gram. At its point of contact with the lever it is pierced with a pin by means of which it is fixed on any point on the lever pierced by the perpen- dicular holes occurring at one centimeter intervals. The attachment is such that the hook is free to swing with the up and down excursions of the lever. Also a weight pan is provided for supporting the weights on the lever. Fig. 10, C. It is made of sheet metal, consisting of a base and two sides. It is of such size that the weights lie flat and fit snugly, but do not bind. At one end, the walls are bent inward slightly so that the weights cannot pass through. When adjusted to the lever, the narrow end is away from the experimenter and the pan is tilted so that the bottom slopes slightly to this end. This is to avoid dis- placement of the weights by the jar that occurs when the muscle re- laxes. The pan is attached to the horizontal arm of the lever by means of a saddle through the middle of which a spring point, slightly longer than the diameter of the horizontal tube, projects. This point is in- serted into one of the perpendicular holes piercing the lever, and when the saddle is placed in contact with the lever, the point, by virtue of its spring quality, binds it firmly into place. The pan weighs ten grams. 16 Weights The forward arm of the horizontal lever being longer than the backward arm, the lever itself serves as a load to the muscle. The recording extension adds to this load. As ordinarily employed, the load amounts to two or three grams, when the muscle is attached five centimeters from the fulcrum. This being the case, in most experi- Fig. 10. Myograph attachments. A. Weights. B. Weight hook. C. Weight pan. D. E, and F. Special weights. G. Counterpoise weight showing end-thrust socket. ments, no additional load is required. However, two special forms of weights are sometimes found useful. One of these is very simple, consisting of a five-gram weight wnth a saddle and point arrangement for attaching it to the lever. Fig. 10, D. The other weight is of a slid- ing type. Fig. 10, E. It is supported in part by a saddle groove which rides on a horizontal lever, but chiefly by a horizontal arm. Fig. 10, F, carried about one centimeter above but parallel with the horizontal lever arm. The weight is attached to the horizontal arm by passing the arm through a hole which pierces it. The arm is encircled at centimeter intervals by shallow grooves, and to one face of the weight is attached a round straight spring which presses into the grooves, by means of which it is readily fixed at any point on the arm. The hori- ErGOOKAI'H — CiAS ClIAMIiKK I'J.IXTKODKS 17 zontal weight is attachcil to the end of the perpeiuHiular arm soL'ket which pierces the horizontal lever. Connection is made by a double friction thrust joint which secures it very firmly yet permits of instant adjustment or removal. Fig. 10, G. The weight is 25 grams and the weight arm adds one gram to the load of the lever. The horizontal arm may he directed in auN- horizontal direction, and thus serves as a Fig. 11. Myograph with pivoted hook weight support. counterpoise which may be desirable when very delicate tissues are used. It is particularly useful when the lever is used for recording the contractions of the hearts of small frogs, as by simply rotating it, the load is instantly and delicately adjusted. Ergograph The ergograph attachments consist of a coil spring, pulley, cord, and finger loop and cord holder for attaching to the myograph. Fig. 12. An L rod serves as the hand holder. The apparatus is assembled as shown in the figure. It is very easily adjusted through a wide range for tension, etc. Gas Chambi^r Electrodes This electrode accessory is designed for studying the efifect of gases and volatile substances upon the irritability and conductivity of nerve. It consists of a short cylinder of hard rubber containing a longitudinal cavity. Fig. 13. It is supported on a tube. The tube com- municates wath the cavity and further serves for the introduction of gas. The wall of the chamber is transversely slit at right angles to the support from above downward, through about four-fifths of its extent, which provides a means for extending the nerve across the cavity. The top of the cavity and the greater part of the transverse slit are closed 18 Gas Chambkr Electrodes by a metal cap bearing a wide flange to hold it in place. The electrode points are placed horizontally in the cavity at a level slightly higher than the bottom of the transverse groove. The points are set at right angles to the holders which, therefore, are perpendicular. The holders are set firmly in the rubber, and their upper free ends serve to connect the wires from the coil or battery. Fig. 12. Myograph with ergograph attachments. The dimensions are such that the electrode may be adjusted to the nerve between the point of contact of the nerve on the myograph nerve electrode and the entrance of the nerve into the muscle without removing the bath from the preparation. It may be lowered so that the nerve is submerged in the bath. This is an advantage in long experiments in preventing undue drying, and also in removing any substance to which the nerve may have been exposed. During the time of passage of the gas, the electrode is raised until the bottom is free of the surface of the bath solution. Gas Chambkk Ei.ixtrodes 19 Usually observations upon both excitability and conductivity are made, Fig. 14. The stimulating current is switched at will from the gas chamber electrode to the myograph nerve electrode by means of the combined primary and secondary key, Fig. 38. Fig. 13. Gas chamber electrodes. Among the advantages of this form of gas electrodes is the ease and rapidity Avith which the nerve may be attached or disconnected from it without injury. Fig. 14. Effect of ether vapor on conductivity and excitability of nerve. A. Vapor applied. B. Vapor removed. C. Response to stimulation of nerve central to gas chamber. E. Response to stimulation of nerve in gas chamber. The gas is passed into the support tube and thus into the chamber, by a rubber tube slipped over its outer end, the other end being con- 20 Thermal Ei.Kctrodes nected with the generator or source of supply. For chloroform, ether, alcohol, ammonia, and the like, i. ^./volatile liquids or solutions of gases, the substance is placed in a small glass bottle or other suitable container, and, if necessary, volatilization is accelerated by placing the container in a vessel of water, the temperature of which can be varied. Fig. IS. Generator. For studying the effect of gases, as carbon dioxide, a compact form of generator is provided, the parts of which are substantially mounted on a base for convenience in handling and storing. Fig. 15. Thermai, EIvECTRODES The thermal electrodes consist of a brass box which is closed excepting for an inflow and outflow tube mounted on the back. Fig. 16. The outflow tube is left sufficiently long to serve also as a support by attaching it to a clamp. Temperature change is effected by circulating T u i:i< M A I. Im.kctkodks 21 vvann or cold solutions throujjh the cavity by means of rubber tubes attached to the inrtow and outflow tubes and to a reservoir, and a vessel for receivinsj^ the outflow. A brass tul)e is soldered to one side of the box. The lower end is closed. Salt solution is ])laced in the tube and into this the bulb of a thennonieter is inserted. It adequately holds and supi)orts the ther- nioiueter since its position is perpendicular, and in diameter it is onlv Fig. 16. Thermal electrodes slightly larger than the thermometer bulb. The salt solution placed in the tube forms a thin layer around the walls owing to its displace- ment by the thermometer and therefore its temperature quickly follows any change in temperature of the metal. And since the temperature of the metal closely follows the temperature of the solution circulating in the box, the thermometer indicates very nearly the temperature of the apparatus. The bottom of the box extends outward for a short distance beyond the front surface and then bends upward at a right angle and terminates at a distance of about one centimeter from the bottom. Thus, a broad slit bounded on three sides by metallic surfaces is formed at the lower margin of the front of the box. A pair of electrodes is fastened to the upper part of the front of the box, from which they are insulated, and extend downward. The points are in- sulated from the front of the box adequately to prevent shortcircuiting. Near the points and near the bottom of the groove through which they 22 Cardiograph extend they are bent forward at right angles and are firmly attached by non-conducting material in holes in the perpendicular portion of the lip. In use, the nerve is carried downward into the slot until it rests upon the electrodes. The slot is then filled with salt solution, the greater part of which it retains through capillarity. Thus that portion of the nerve resting upon the electrodes is surrounded by salt solution, the temperature of which must closely follow temperature changes as indi- cated by the thermometer, for relative to its mass, a large area of the surface of the salt solution is in direct contact with the metal of the box and lip. The design and dimensions of the thermal electrode are such that it may be readily adjusted to the nerve without removing the nerve from the myograph electrode or lowering the bath. When it is desired to produce a change in temperature, the thermal electrode is raised until it is free of the surface of the bath solution ; or the same end is accomplished by lowering the bath. To lower or raise the temperature, cold or hot brine is circulated through the cooling chamber. This form of thermal electrode presents a ready means of studying the effect of temperature and with the expenditure of but little time. In addition, the temperature is under adequate control and wdde fluctua- tions can be produced at will. Cardiograph Isolated heart muscle is studied by attaching it to the fixed and movable points of the myograph. The base of the auricles is trans- fixed on the stationary point, and the apex of the ventricle on the movable point. Or the heart may be transfixed at the auricular- ventricular junction by the fixed point and either the apex of the ventricle or the base of the auricle transfixed by the movable point. Or the auricles and ventricles may be separately attached to the points. Tracings taken by this method are shown in Fig. 17, B and C. In the same way strips of heart tissue are attached to the points and studied. The heart may be studied in situ in much the same way. After removing the anterior wall of the chest, the animal is brought upward in such a position that the points transfix the heart. By using longer points the lever may be adjusted to the heart of a cat or dog. Two CAKPKlOKAril 23 levers may be attached to one heart and both auricular and ventricular contractions separately and coincidently recorded. The lever is also adapted to studying the heart in situ by the sus- pension method. See tracing, Fig. 17, A. For this purpose the points and electrodes may be removed. The posterior support rod is removed Fig. 17. Heart tracings from a 31.5 gm. frog. A. By suspension method with regular myograph. B. Heart isolated and auricles and ventricle attached to points of myograph. C. Ventricle only attached to points of myograph. and attached to the far side of the frame. Or it may be removed and the lever held by clamping the anterior support rod. The animal is placed beneath the lever and a thread attached to the apex of the ventricle or auricles is carried upward and fastened about the posterior (horizontal) arm of the lever. A holder is provided for fastening the thread. By thus employing two levers at the same time, both auricular and ventricular contractions may be recorded. This method is especi- ally useful for turtles. 24 Cardiograph For studying the frog's heart in situ, a pad and support method is convenient and effective, Fig. 18. The heart is supported on a metalhc finger or spoon rest which is connected through an insulation block to the frame above by means of a screw passed through the posterior su])port rod socket. The pad consists of a small disk of cork (which may be cut from the end of a stopper) attached to the movable point Fig. IS. Myograph arranged for studying frog's heart in situ. A. Insulated heart support. Note tubular socket on side of strip for the electrode connection. B. Cork pad on tissue point for transmitting niov€ment of heart. C. Counterpoise weight. by transfixing it near the center. The point emerges from the lower surface of the disk so that it slightly penetrates the tissue and thus serves to prevent horizontal movement between the pad and the heart. The frog is supported on a board clamped to the stand support rod below the lever, Fig. 19. By a slight movement of either the lever or frog board the heart may be instantly adjusted to or removed from the lever. In all the above experiments where delicacy of poise of the lever is an essential requirement, this may be instantly carried out by means of the right angle weight support bar, or sj^ecial right angle counter- poise provided for the purpose, Fig. 10, G. Attachment between the weight and the lever is made by means of a double end -thrust contact between the socket on the weight and the tubular cup provided on the top surface of the lever on a perpendicular line through the fulcrum. Hl.IX'TRODKS 25 It is easy to ol)tain the desired adjustment of load by rotating tlie weight horizontally. To stimulate the heart directly, in the pad and rest method of attachment, an electrical contact tube is provided on the metal portion of the rest, and for the other contact the tube on the frame is employed. Thus an electrical current may be transmitted between the movable point and the rest through the heart tissue placed between them. Fig. 19. Myograph arranged as frog cardiograph and mounted with frog board and de- tachable electrodes. Insert shows adjustment to frog. Simple Electrodes A pair of adjustable, detachable electrodes is shown in Fig. 20. The electrodes consist of a support rod attached to a fibre block into which the electrode point holders are fixed. The points are sufficiently 25 Special Cardiograph long to render adjustment easy. Near their free extremities they are bent outward at an angle to provide a rest for the nerve. Electrical connection is made by inserting wires into the top ends of the holders. In the experiments on the frog as just described, the electrodes are supported on an L rod, which in turn is clamped to the stand support rod sleeve below the clamp wdiich holds the frog board. Thus it is possible to adjust the electrodes quickly in any position desired, and since they are rigidly supported they maintain a very constant adjust- ment to the nerve. Fig. 20. Adjustable electrodes. B. Adjustable electrodes with electrical contact surfaces in posterior end of support rod. An insulating collar similar to the one shown in Fig. 2, G, is provided. This electrode is convenient for use on frogs and turtles, and in certain experiments on mammals. It may be used for stimulating muscle directly, as in the case of the turtle's heart, by lightly placing the lower surfaces of the bent ends against the muscle, in which posi- tion it may be held by a clamp attached to a support. SpEciaIv Cardiograph A special form of heart lever has been designed for studying the heart by the suspension or the pad and rest method. Fig. 21. It is employed precisely as has been described for the regular lever and presents no points of superiority other than those conferred by the fact that being designed especially, it is somewhat smaller, particularly due to cutting down of the frame, and to the absence of frame accessories. The movable point is not attached at the fulcrum, but one or two centi- Frog Holder 27 meters in front of it. Its chief advantage lies in the fact that, due to cutting down of the frame, in the pad and rest method a shorter mov- able point can be employed and thus a greater magnification secured. Fig. 21. A. Special cardiograph. Tracing taken with above form of cardiograph. S. Sinus. A. Auricles. V. Ventricle. B. Bulbus. Frog Holder — Form I The frog holder consists of a wooden base topped with a thick pressed cork pad, the two being firmly united by cement and brass brads. Fig. 22. The dimensions are 150 x 100 x 10 mm. To one side 50 mm. from one end a support rod is attached at right angles to the long dimension by means of screws inserted into holes in the broadened end of the rod and turned into the bottom of the board. This serves to support the board on the stand support rod by means of a clamp. Form II The adjustable form of holder shown in Fig. 23 is convenient for certain experiments as it permits of a wide range of adjustment. A threaded socket provides for the direct attaching of a support rod for 28 Frog Holder mounting electrodes and a hole near the forward outer corner for microscopical observation of circulation in membranes. Frogs are fastened to the holder by means of pins, as the method is simple, rapid, efficient — and pins are easily obtained to replace those lost. The holder when assembled is water-proofed by soaking in hot paraffine, so it is easily cleansed by wiping with a moist cloth or sponge Fig. 22. Frog holder. Form I. or washing in cold water. Obviously, hot water should not be applied to it. It is sufficiently large for ordinary frogs, and not being cumber- some, takes up but little room. It is readily adjustable to any position desired and being designed especially for use with the myograph, it meets all ordinary requirements. ( See Figs. 23a and 23b.) Form III This form of holder, Fig, 24. is particularly useful for graphically recording results in reflex experiments, character and site of action of drugs with the circulation intact, etc. (cf. Am. Jr. Phys., 1910, xxvi, 329). Owing to the ease with which accurate and stable adjustments can be made, and the absolute control of the current, very accurate results are obtained. I'koG lllll.DKR 29 'iMic wootlen base is screwed to an iron shelf l)racket, which is jirovidcd with a socket and set screw for attaching to a stand rod. The floor of the base is covered with a cork j)ad which is boiled in paraftine and laid while the paraffine is melted and pressed until the parafitine sets. The anterior third of the floor has a double thickness \!\ "^ ^ Fig. li. Adjustable frog holder. Form II. A. Side view. B. Bottom view. 1. Adjustable support rod. 2. Electrode support rod socket. 3. Hole for microscopical examination of frog's web. of cork, the posterior edge of which is beveled. Owing to the treat- ment with paraffine, the floor is water-proof, and, therefore, is easily kept clean. And being of cork, pins may be readily thrust into it to hold the frog. Three pairs of electrode holders w-ith adjustable electrodes are mounted along either side. The holders are so spaced that the gastroc- nemius muscle, sciatic nerve, and fore limb skin or nerves may be stimulated. Or all three pairs may be adjusted to the sciatic, as in studying the local action of reagents on the nerve trunk. A tubular metal container is provided for the electrodes when not in use. A special multiple key and switch serve to control the current to the 30 Turtle Holder electrodes. The construction of the key is the same as in the combined primary and secondary cut-out key, switch and commutator, Fig. 38. No unipokir stimulation can occur. Fig. 23a. Frog holder assembled with special duplex myograph clamp and two myographs and two pairs of electrodes for simultaneous tracings from both gastrocnemius muscles in situ. The tendons of the muscles are connected directly to the levers by the tissue points. Turtle Hoi.der The holder, which is of wood, consists of a base measuring 200x200x25 mm., and two rests measuring 45 x 45 x 150 mm. The rests are attached to opposite sides of the base so that their facing surfaces are parallel and about 110 mm. apart. Fig. 25. The central portions of the upper inner corners are concave for a distance of 110 mm. and a depth of 10 mm. in the middle. The base and rests are finished with a water-proof paint or varnish. Two metal pins are set obliquely in one end of the base for attach- ing the head. A nickeled support rod 10 cms. long rising from the Tuning Fork 31 forward end of one of the rests provides a means of attaching elec- trodes, etc. A terrapin or tnrtle is mounted by placing it back down upon the holder. It is lield in place by pressing with one hand upon the ventral plate. A short hook formed on one end of a steel rod, Fig. 25, D. is then pressed under the "chin" and ihc head withdrawn and crushed ^1 / 1/ rf 1 * jjA^kt. 1 M^^ 1 1 -^^ Fig. 23b. Side view of assemblage to illustrate the method of supporting the frog board and electrodes by means of L rods. The board clamp is not shown. All clamps on the main support rod should be atttached to a sleeve for convenience of perpendicular adjust- ment to the drum. The tendons of the muscles are connected to the myographs by means of threads and special extensions attached to the levers. The electrodes are adjusted to the sciatic nerves. (For sleeve, see Fig. 1 or 16.) with gas pliers. A piece of wire is then bound tightly about the upper part of the neck to prevent hemorrhage and the pliers removed and the neck placed between the bars of the holder and fastened by means of the ends of the wire. The feet are then fastened to the ends of the rest block with nails. Roofing nails, which are short, thick, and sharp-pointed, are convenient for this purpose. The ventral plate is then removed with a hack saw and knife and any bleeding vessels ligated. when the preparation is ready for use. Tuning Fork The tuning fork made by the Harvard Apparatus Company is modified to the extent of slittinsf one of the ends near one side to 32 TuxiNG Fork facilitate attachment of a writing point. Fig. 26. ]\lade of good quality of paper or of thin celkiloid and fastened with seahng wax, the writing points give excellent results and rarely need adjustment. For starting the fork to vibrate, a block of hard wood, measuring 28 x22 X 23 mm. and e(|uipped on one side with two brass pins 4 mm. in diameter screwed lirmly into the block, is used. The pins are set Fig. 24. Compound frog holder, Form III, and key. The frog holder is e(iuipped with two special myographs, but the regular form can be used. The six pairs of binding posts mounted on the holder serve as electrode holders. An electrode is shown in the right of the figure. The cylindrical case attached to the side of the holder is a container for the electrodes when not in use. On the key the binding posts marked P and P' are connected in the primary circuit, and S and S' in the secondary circuit of an induction coil. The battery current may be lead to the tissues by connecting to the posts S and S'. 13 mm. apart. They project 7 mm. from the surface of the block, and their facing sides are filed in a sloping manner so that their nearest point of approach is near their free ends. The appliance is attached to the fork by springing the bars together with one hand and sliding the projecting pins on the block over their outer surfaces from their free ends backward. Owing to the sloping surfaces of the pins they bind on the fork near their points only, and, therefore, they firmly hold to the bars after the hand is removed. To set the fork vibrating, Tlning Fork 33 the block is riMiiovcd by a tuniin.L; niovcinriit from hcfore l)ack\var(l. 'I'he backward ods^o of the face in contact with the e -"-^^ J4-2J ;>■'«. 7,7 a?i«f io Fig. 51. Calibration test of automatic myograph key. Drum turned with hand rotator. Figures beneath signal tracing indicate screw turns in full divisions. Fig. 52. Heart tracing. Automatic stimulation. Ventricle of turtle's heart. The dots on the tracings indicate the point of stimulation. The signal tracing provides a check on the efficiency of the contact. DUCM CilN'TkOI. t>T.\M) 53 models. With llic stand and its attachnuMits it is a simple matter and requires but little lime to take aeeurate traein<,^s showing the phases of a simple museular contraction, summation of stimuli, superposition of contraction, rate of nerve im])ulse, refractory period, etc. Fig. 53. Drum control stand, Form I. Form I The base of the stand is of wood, blackened and wax finished, Fig. 5.S. It measures 408 x 176 mm. and is 22 mm. thick. The bottom surface is provided with three foot pads. The upper surface is pro- vided with depressions for the foot rests of the kymograph and two attached clamps of nickeled spring brass for holding the kymograph base. At the front margin is the wooden pulley support which is finished like the base. The pulley is nickeled brass. To one side of the pulley support is the support for the apparatus, hand drum rotator, and drum brake. Fig. 54. Behind this at the posterior margin of the 54 Drum Control Stand base is the key support. Both supports are of heavy nickeled brass tubing screwed into bases of the same material, which in turn are firmly attached to the wooden base bv heavy nickeled brass screws. t kza 5 Fig. 54. A. Drum rotator; see also Fig. 71. One division of the rotator moves the drum through one milHmetfer. B. Drum brake; see also Figs. 55 and 1. Form II The base is of compact form, Fig. 55. It is made of iron and is given a smooth water-proof finish. It is provided with three leather- soled feet. A rigid arm rises perpendicularly from the back of the base and terminates above in an adjustable hinged extension, wdiich carries a pointed bearing to engage in a bearing socket in the screw on the upper end of the drum sleeve. Thus, support is given to the free end of the spindle, wdiich eliminates excessive vibration when the drum is checked and stopped at fast speeds, especially when heavy weights are employed. The base weighs 8 pounds, and this further serves to eliminate vibration. The pulley, stand and key rod and drum base DlU'M A\n Co.VTKOI.I.Kk 55 clamps arc nickeled hrass. 'J\vo additional ijullcys may be mounted on the perpendicular arm, one near the base and the other at the top so that it is not necessary for the front pulley to j)roject beyond the edge of the table, but for ordinary purposes the additional ])nlleys are superfluous. Fig. 55. Drum control stand. Form II. Recording Drum and Controller The drum, Fig. 56, is mounted on a substantial cast iron base. It is driven by a weight and cord, Fig. 57. Any speed from a few milli- meters per minute to 500 or more per second is easily and quickly 56 Drum and Controller attainable. All speeds may be regulated by the weight. In addition, the slower speeds are controlled by a viscosity brake. The spindle and brake pulley comprise a single moving part. The construction throughout is rugged and designed for heavy service. The design is such that little time is required for dismounting, assembling or Fig. 56. Recording drum and controller. adjusting. Simple, strong, and efficient attachments are provided for all ordinary needs. The tubular posts arising from the base provide a means of attaching a hand drum rotator and drum brake for high speed work, Fig. 54, and a drum stimulating key, Fig. 30. To the anterior of these posts is attached a universally adjustable recording Dkl:M AM) CdXTUdl.l.KR 57 apparatus stand, thus cliniinatini:^ the need of separate apparatus sup- ports. The base is smoothly finished in l)lack and all brass ])arts are nickeletl. The drum itself is of the Porter east aluminum pattern. It is mounted on a sleeve support, Fig. 59, to which it is fixed at any height by a substantial lock on the U])per end. It is prevented from turning by a key on the sujiport and a slot in the lower end of the drum. Thus Fig. 57. Weight and cord. The weight unscrews in the middle, the connector i)in re- maining with the lower half. Fig. 58. A. Swinging arm and upper liearing. B. Anterior pulley support. Measurements are in millimeters. accidental moving or creeping of the drum in any direction on the sup- port is guarded against. Yet it is instantly adjustable to any horizontal or perpendicular plane. A combined drum brake and key pin is set, with insulation, in the lower end of the drum. The drum is mounted on the spindle of the controller. The drum support is tubular brass, Fig. 60, A. The upper end is closed and inside it is provided with a centered cone pointed, hardened steel bearing which bears on the upper end of the controller spindle. This bearing carries the weight of the support and drum. The outer surface of the closed upper end of the support is provided with a centered socket in hardened steel to receive 58 Drum and Controixi'.r the drill steel pin of the upper controller bearing. The inside diameter of the support is somewhat greater than the diameter of the controller spindle and near the upper end a brass ring bearing is provided, which is accurately fitted and adjusted to the spindle, which is drill steel, so that the drum may turn smoothly and not have undue "p^^y-" The Fig. 59. Drum mounted on sleeve. Fig. 60. A. Drum support sleeve. Reel. C. Spindle. lower end of the support is open. To the outer surface near the lower end is affixed an encircling brass friction band. It is acted upon by the friction arm and screw of the reel, and thus the support and reel are united with any desired degree of rigidity. The end of the support below the friction band fits accurately into a circular slot in the upper end of the reel and serves to aid in centering and maintaining the two Drum an'd Controf.i.kr 59 in position. The wall around the lower end of the support is beveled on l)oth sides to insure its entering the slot smoothly without special attention when the support is placed on the spindle. The length of the drum support is ample to provide for all perpendicular adjustments of the drum, and for smoking the drum paper without soiling or burn- ing the hands. The reel, Fig. 60, B, carries the weight cord and transmits the turning force to the drum. It is of tubular brass of the same trans- verse dimensions as the drum suj)port. Inside, near cither end, it is provided with circular bearings accurately fitted to the controller spindle like that of the support. The upper end is provided with a slot to receive the lower end of the drum support. Also it carries a self- adjusting friction lock for connecting the reel and drum support. Owing to the extensive and accurate engagement of the lower end of the drum support and the slot in the reel and the self-adjusting feature of the fric- tion lock, the pressure of the friction arm and of the screw to the oppo- site points of the friction band of the drum support is equalized and there is no danger of causing the reel and drum support bearings to bind on the controller spindle when the two are locked together. The blunt cone point of the locking screw centers on the beveled surface of the friction band, and as this surface is on the upper margin of the band, the reel and drum spindle are drawn tightly together end to end when the screw is tightened, thus causing end as well as side pressure at the joint. A heavy collar is affixed to the lower end of the reel. In this, a knot holder, consisting of a pin terminating in two blunt parallel arms is set for instantly attaching the weight and cord to the reel. The collar also carries a set screw for locking or releasing the reel from the controller spindle. A stop in the form of a collar on the spindle. Fig. 63, prevents the reel from being set at so low a level that an imperfect connection with the drum support might cause binding of the bearings on the spindle. The drum is removed from the controller by (1) locking the reel to the spindle; (2) unlocking the drum support from the reel; (3) turning the hinged upper bearing arm upward and backward; (4) lift- ing the drum support (or sleeve) wdth the drum ofif the controller spindle. To mount the drum, the processes are reversed. To wind the reel, the drum is mounted and locked to the reel. The reel is then unlocked from the spindle, the cord of the weight placed over the pulley 60 Drum and Controller with the weight suspended and the knot at the end of the cord placed in the holder and the drum rotated backward, i. e., anti-clockwise until the weight is raised near to the pulley, when the reel is locked to the spindle. The drum is conveniently rotated by manipulating the upper end of the reel with the fingers of one hand. The cord should be evenly wound. This is insured by slightly depressing or raising it between the reel and pulley if necessary. The weight provides an even tension during winding. For slow and moderate speeds, i. e., up to 30 to 50 millimeters per second, the viscosity brake is used. Therefore, the reel remains locked to the controller spindle and the drum is started and stopped by releas- ing and clamping the spindle. The rate of the spindle is adjusted by the speed regulator, or by increasing or decreasing the weight, or both. For faster drum speeds, the drum and reel lock is released until the joint turns freely and the milled surface of the drum stop pin is adjusted to the drum brake and stop. The drum sleeve and reel are then relocked together and the reel released from the controller spindle. When released by the brake and stop, the drum and reel rotate inde- pendently of the controller spindle, %. e., they rotate around it owing to the inside support bearing at the top of the sleeve which carries the weight on the end of the spindle, and the three inside ring bearings. The drum is steadied and with the spindle is held perpendicular by the socket in the top of the sleeve and with the pin carried by the hinged arm of the rigid support rising from the controller base. For stationary work, that is, when records are made as perpen- dicular lines, the drum being turned slightly between such records, the reel is locked to the spindle and the drum sleeve released from the reel. If the drum is turned by hand enough friction may be maintained in the joint as may be desirable to insure the immobility of the drum while records or notes are being written on the smoked surface. If rotation is by means of the hand rotator. Fig. 54, A, the sleeve-reel lock is completely released and the sleeve raised slightly in the drum (say one millimeter), so that the weight may be carried by the rotator, thus insuring its proper action. The controller spindle, Fig. 60, C, is of drill steel. The upper end is free when the drum sleeve is removed. When the drum is mounted the upper end forms a bearing with the inside cone-pointed bearing of the sleeve and it is centered to the pin of the upper outside bearing, DkLM and CoNTROl.I.KR 61 that is, the bearing between the socket in the upper surface of the end of the drum sleeve and the pin carried by the hinged arm of the upper I)earing support, through the ring bearings in the drum sleeve and reel. The lower end of the spindle is cup])ed and rests upon a hardened steel ball, which is set in a socket in the floor of the viscosity chamber of the controller base. Fig. 61. The ball rests ujjon a hardened steel Fig. 61. Cross-section of base of drum stand. Note the lower bearing, the viscosity chamber, pulley and brake, the air chamber of the cap communicating with viscosity chamber through a hole in the diaphragm, and the double grease cup seal in the air chamber. The leather soles of the drum feet are shown. floor. The socket is provided above with a narrow circular brass bear- ing surface, which is fitted to the lower end of the spindle. Just above the lower bearing the spindle carries a brass oval- faced pulley, which is set rigidly to the spindle, after which the outer face is turned and polished very accurately, as it is by means of this surface that the speed OJrEi: Fig. 62. Diaphragm interposed between viscosity and expansion chamber. Note lower half of grease seal and hole for expansion of glucose. of the spindle is regulated. Above the pulley the spindle passes through a metal diaphragm. Fig. 62, but does not come into contact with it, excepting through a grease cup seal on the upper surface of the dia- phragm. Passing upward the spindle emerges from the viscosity chamber cap but does not form contact with it save through another grease cup. It then passes through the garrotte clamp. Fig. 63, by 62 Drum and Controller means of which, at viscosity speeds, the drum is started or stopped. Just above this point the spindle carries the narrow circular stop for limiting the position of the reel. Fig. 63. Top, side and bottom view of spindle, viscosity chamber cap, and brake. To the right is a top view of the clamp for stopping the drum. The spindle has, therefore, two bearings, the upper being of the pin and socket type, the lower being of a combined ball end thrust and annular side type. The ball end bearing carries all of the load and is subjected to the severest duty of any of the bearings, but it is capable of sustaining many times as much strain as can be exerted upon it through the use to which it is here put without danger of appreciable wear or damage. The edge bearing surface of the annular part of the lower bearing has only to withstand the pull of the weight which is applied to the spindle at the level of the reel, and this only at the viscosity speeds. Therefore, it is subjected to but little wear. At fast speeds, that is, when the drum is rotated upon the spindle, the garrotte Drum and Controli.kr 63 clamp rigidly holds the spindle and thus relieves the lower hearing of all duty. All hearings possess a very large margin of surplus strength and are capahle of unlimited usage without material wear. Occasion- ally a drop of oil or a very little vaseline should he applied to the top and side of the sj)indle and to the outside top hearing to insure con- stancy of rate at high speeds, hut no appreciahle damage will result from failure to do this. Of course, if the parts are allowed to rust, perfect performance cannot he expected. Fig. 64. Drum viscosity brake. Dismounted to sliow construction. The regulator is shown below. The speed of the spindle is regulated through the viscosity brake, Fig. 64, and hy means of the weight. The brake pulley is embraced at opposite points of its face by brake shoes faced with wool yarn. iajjJjJ4dtJiliil|iJiiJiiijaijmilf(llll(flllliUUiiiiliitlllJ:^ Fig. 65. Drum test. The upper four tracings are of a Jacquet time marker recording seconds on a drum controlled with a viscosity brake. The speed may be set for one revolu- tion in 30 minutes or longer. By adding weight a much faster viscosity regulated speed than that shown in the fourth tracing may be obtained. The two tracings at the bottom are of a tuning fork giving 100 D. V. per second. The drum sleeve rotated on the spindle. A wide range of speed may be obtained by this method by altering the weight. 64 Automatic DuplKx Circuit Controller The yarn is wrapped transversely. The faces of the shoes next to the pulley are doubly concave, so the yarn surface that acts upon the pulley is elastic as it extends between the edges of the horizontal concavity. Also, this permits of automatic adjustment of each yarn strand to the pulley without binding and insures an even and constant distribution of glucose to the surface, the cavity between the yarn and metallic sur- faces being occupied by this substance. The shoes are mounted on a pair of self-adjusting U-arms. The arms are approached or separated by a quadrant lever and calibrated screw on top of the base which are provided with indicator scales. The faces of the brake shoes but lightly come into contact with the polished pulley face, and wear at this point is practically a negligible factor, but the lever is adjustable so any material wear is easily compensated. Fig. 66. Tests of drum'for uniformity of rate at fast speeds. The test was made with one winding of the weight cord. Especial care was not exercised in the experiment. The results would indicate a variation of only a few per cent. When such possible error is con- sidered as in measuring a tracing for latent period, it becomes practically negligible. (Cf. Figs. 33 and 34.) The viscosity chamber is filled with glucose and covered with a metal diaphragm to insure uniform action of the glucose on the pulley. The diaphragm. Fig. 62, is of cast brass and provided with a grease AlTDMATIC Dl'IM.KX ClKCL'lT CoNTUOI.I.KR C)5 cup seal surrouiulint;- the s])iii(llc. It is fastened to the upjjer surface of the viscosity chanil)er cover, and separates the viscosity chamber below from the air chamber of the cap above, except for a small hole in the diaphragm, which serves as an expansion outlet for the glucose. Vis- cosity changes due to temperature variations introduce no practical difficulties, as such changes are so slight during the course of an or- dinary experiment as to be negligible. For special use, a temperature compensating attachment may be introduced. The results shown in Figs, 65, 66, 68, 72, 33, 34, 51, 52, etc., give a good idea of the efficiency of the drum under various conditions. Combined Priiniarv and Secondary Circuit ControllivR The controller. Fig. 67, automatically performs the following operations : 1. Closes and opens the primary circuit at any rate from one per minute to 100 per second. 2. Makes uniform closing contacts and opening interruptions. 3. Eliminates closing or opening secondary currents or permits both to flow through the electrode circuit. The controller is actuated by an electro-magnet. The rate of in- terruption is regulated by an oil brake and is readily adjustable. Uni- form electrical contact is made by a coil spring acting eccentrically on a rocking arm bearing a contact surface. All parts are adjustable. The contact period is short, being under 0.03 second at slow speeds and less at rapid speeds. The contact is opened by the movement of the magnet bar in response to the pull of the magnet. No special retarding force is opposed to the movement. The oil brake retards closure of the contact. It recjuires one to two amperes of current. One or two dry batteries are adequate. When used with an induction coil they are wired in series. The secondary controller is operated from the same magnet. It automatically short-circuits the secondary before closure of the primary contacts, and breaks the short-circuit while the primary circuit is closed. It is connected in parallel with the secondary circuit. It is easy to extend the short-circuit attachment so that it may be adjusted for eliminating either opening or closing shocks. 66 f^ flj '-T " -. — u— o c S c ^ o o K :»£! CM 5 =~ . i+H . O O - -^ (u ^ -5 J-: "S = 1^ M ?;• X . ^ rt M re o rt; ' c''." Son ■a !- 11. - w o 4J o 1 i^ci',>> 5 niagi to b ar. 5, T 0 u > ^ sc s c >. n! '-■ .r= . ■- 0 S°|^ So >. •r ^0-^ - r! 2 !! &^'1i r 4^ = ? 0 5 r i;_ M V3 ., f! -.|o^| o_ otAl 5 . 0 0 0 ►4 ;i: j= — 0 . 0 0 a 0 u r-; K OJ 0 (U U (U .2 0 ^ 0 5J •-: 5 ;iu ort £^ n "m g - i 1^ - fe-5 if .>.>iS W El.. <-£!>"-> •r V; jC S^ p o. rt w ^ ^ ^ ro 5; ?c'^ Co S'^' = « — — 1; — u u - — - r uSi — ' = j= v: OS -a < \ u ■> a m 1-2 3 p a 67 i sj /■ /' I nm 'II s a nn m i m m m m i v n ? .-/ ii ; ? /; n i; ■I ini in n rii ii i n u riirn w mmnrrmi an n ii nni ifr TiiiiniJinrnnf D ^ 3 R 6 T iiiiiiuiiiiiiiiiiiiiiiir D. Fig. 68. Primary interrupter test. Tracings 1 to 7, inclusive, taken with electro-magnetic signal; tracing 8, Jacquet time- marker set for seconds. Drum speed was the same for all tracings. Same as A, only tracing 7 is by Jacquet time-marker set for seconds. Primary interrupter set for seconds with periodic groups of rapid interruptions controlled at will. Thus used it serves as a base line, time, and signal recorder. The induced current during periods of rapid interruption may be led to stimulating electrodes by means of the secondary hand key. Automatic periodic grouping of interruptions with control of time between periods and number and rale of interruptions in each period obtained by connecting two inter- rupters. 68 CoMiuNED Coil and Current Controllers The mechanism is substantially constructed and is very durable. It is easy to adjust and requires very little attention. It closes and opens the circuit in a uniform manner and is easily adjusted while in operation for any rate from one per minute or slower to 100 contacts and interruptions per second. With a battery and signal it may be used as a time marker ; or connected in the primary circuit of an induction coil, to open the circuit uniformly to closure with a hand key, or to both close and open the circuit automatically at any rate desired within the limits mentioned. Fig. 68. Fig. 69. Myograms illustrating cut rent control with the interrupter and rheocord. Combined Coil, Current Controller, Rheocord, Primary and Secondary Keys, Switch and Commutator (Combined Coil and Current Controllers) The various parts of this apparatus. Fig. 70, are mounted on a three-ply wooden base measuring 223 x 190 x 16 mm. At the back the base projects upward 75 mm. Upon the upper edge of the back are CoMlilNKO Coil. AN!) ClKKKNT Co.NTKdl.l.KRS 69 mounted the primary and secondary l)inding posts. The primary ilivision of the circuit controller is connected in ])arallel through the primary hand key with the rheocord and coil. The rheocord may be removed from the circuit by means of a contact screw. It may be so mounted that it can be used indej)endently of the other parts of the apparatus. The coil is of the Porter form. The core of the primary Fig. 70. Combined coil and current controllers. may be removed. The secondary may be raised perpendicularly. The finer degrees of the stimulating current are obtained with the rheocord. The secondary leads are connected with the secondary key leads and with the secondary division of the current controller. The circuit may be broken to the controller by means of a contact screw. Also, the circuit to the keys may be broken by another contact screw^ By opening both these screws the secondary keys are isolated, so they may be used for a battery current. A pair of binding posts on the key leads serves for such connection. Commutator connectors (see Fig. 38) are pro- vided. When not in use, they are attached to the back side of the base. 1 70 Combined Coil and Current Controllers In Fig. 71 the apparatus is shown in use with the drum. The tracing shown in Fig. 72 was taken in this manner. Fig. 71. Dnnn, myograph, signal, and combined coil and current controllers. Fig. 72. Myogram taken with apparatus as shown in Fig. 71. Fig. 13. Drum and attachments and accessories in case. Fig. 74. Drum case closed. It measures 8J^ x 11 x 20 inches. PRESS OF KOHN AND POLLOCK, INC. BALTIMORE COLUMBIA UNIVERSITY This l)C)ok is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the rules of the Librarj' or by special ar- rangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE C2e(63e>M50 Civ.thrie