Herbert Elftman

The force exerted by the ground in walking

SummaryA method is described by means of which the resultant force exerted by the ground on the body during walking is recorded in three components and the point of application of this force is determined. The path of the point of application in a step is illustrated and discussed in relation to the variations in the three components of the force. The data obtained may also be used in a study of the movements of the body as a whole.

A Chrome-Alum Fixative for the Pituitary

A fixative containing 5% chrome alum, 5% formalin and 5% mercuric chloride is capable of fixing the pituitary gland of the rat at room temperature overnight so that it can be stained with periodic acid-Schiff and with aldehyde-fuchsin, as well as the usual counterstains. The use of trivalent chromium in this fixative is of particular interest because of its importance in the cross-linking of proteins during tanning.

PHOSPHOLIPID FIXATION BY DICHROMATE-SUBLIMATE'

Phospholipids may be preserved for study in paraffin sections by fixing the tissue 1 to 3 days at room temperature in 2.5% potassium dichromate dissolved in 5% mercuric chloride. After this dichromate-sublimate fixative and paraffin embedding, the phospholipids are readily stained with Sudan black.

A direct silver method for the Golgi apparatus.

Direct immersion of fresh tissue in a solution of silver in formalin at pH 4, followed by development in hydroquinone-formalin, results in consistent silvering of the Golgi apparatus. The time required depends on the penetration of the tissue, two hours for each step being adequate for routine purposes. Proper general fixation of the tissue is enhanced by returning it to a fixative for the customary periods of time. A weak solution of iron alum is suggested as a convenient method for reducing the intensity of the silver image in sections, when that is desired. Replacing the silver image with gold allows it to survive more drastic subsequent treatment, such as periodic acid oxidation.

Combined Aldehyde-Fuchsin and Periodic Acid-Schiff Staining of the Pituitary

Aldehyde-fuchsin and the periodic acid-Schiff procedure can be applied in sequence to the same tissue section and combined with a stain for acidophils, such as orange G, for routine analysis of the pituitary. This is made possible by fixation in a mixture containing 5% chrome-alum, 5% HgCl2 and 5% formalin; control of the pH and the activity of the aldehyde-fuchsin; and increased sensitivity of the Schiff reagent, effected by reducing its SO2 content. Although designed especially for the pituitary, the procedure is also applicable to other histological problems.

HISTOCHEMISTRY OF UTERINE PIGMENT IN VITAMIN E‐DEFICIENT RATS

The pigment which develops in rats deficient in vitamin E not only serves as an index of the progress of the deficiency but may also provide a clue to the derangement of metabolism which leads to its production. The chemical characterization of the pigment is, consequently, of interest as a definition of an end point in metabolism. It is also necessary as a means of comparison between this pigment and others formed under different circumstances. Many of the salient characteristics of the pigment of vitamin E deficiency have been determined by previous investigators. The methods of histological staining which have been used for its identification have also given information concerning its constitution. Attempts to extract the pigment from adipose tissue by Dam and Granadosl and from uterus and skeletal muscle by Moore and Wang2 have led to contradictory suggestions concerning its composition. The present investigation has been restricted to the application of histochemical methods to tissue sections. Although these methods involve restrictions of temperature, solubility, and brutality of reagent, they have the unassailable advantage of guaranteeing that the observed reaction is due to the pigment itself and not to some artifact of extraction. The investigations reported here were conducted entirely on the pigment present in the smooth muscle and associated macrophages of the uterus of rats on a vitamin E-deficient diet. Although there is reason to believe that this pigment is identical with that which develops in other organs in vitamin E deficiency, the term “uterine pigment” will be employed, since not all of the reactions reported here have been tested on the pigment of other organs. As a matter of convenience in this paper, it will be understood that the hemosiderin in the uterus is not included in the designation “uterine pigment.”

The rotation of the body in walking

SummaryThe rotation of the body as a whole during movement may be studied by determining the angular momentum. In walking, the angular momentum about the lateral axis is larger than the other two components. It also differs from them in that it goes through a complete cycle of change for each step, instead of a cycle for each two steps.The angular momentum of the body indicates that the body as a whole rotates about the foot which is preparing to leave the ground in such a fashion as to incline the body toward the advancing foot. After the first foot leaves the ground, the direction of rotation is reversed and so continues, as far as rotation about the X and Z axes is concerned, rotating the body about these axes toward the position in which the foot will be placed. About the transverse axis, however, this change in direction of rotation results in backward inclination, but a second change in the direction of rotation about the lateral axis results in forward rotation before the foot is planted.The rate of change of the angular momentum gives the external torque which is acting on the body. Since this torque is the product of the external force and the position of the point of application of this force with respect to the common center of gravity of the body, the external force being known, the point of application can be determined.

Histological Methods for the Demonstration of Gold in Tissues

Two methods for the demonstration of gold in tissues are described. The tissue is fixed in neutral formalin, embedded in paraffin, sectioned and run down to water. In the SnCl2 method, modified from that of Christeller, it is then incubated for 24 hours at 56° C. in a mixture of ten parts of 5% SnCl2·2H2O and one part of concentrated HCl. The interpretation of the results obtained by this method is frequently difficult because of the presence of accessory precipitates and the presence of the normal pigments of the tissue. This has led to the development of a new method, in which the sections are incubated for periods varying from 24 hours to 6 days at 37° C. in 3% H2O2. The gold is reduced to the metallic state, the interfering tissue pigments are bleached, and, since no metallic ions have been added, accessory precipitates do not occur. After both methods, the sections are washed thoroughly, run up, and mounted in damar.

A Micro-Bioassay Method for Estrogen.∗

Summary Very small amounts of test substances can be assayed for estrogenic activity by injecting them into the lumen of the castrate uterus of rat or mouse and observing hypertrophy of the Golgi apparatus and depletion of basal phospholipid of the epithelium. Additional criteria are appearance of glycogen in the uterine muscle of the rat and mobilization of alkaline phosphatase in the mouse.

BODY DYNAMICS AND DYNAMIC ANTHROPOMETRY

Man exhibits some of his most distinctively human characteristics in his pattern of motion. The ease with which he spans distance and executes intricate maneuvers testifies to the harmony that exists between the construction of the body and its motor mission. Quantitative appreciation of the human mechanism antedates both anthropology and biophysics and is not the exclusive property of men of science. Calipers and equations cannot compete on even terms with the experienced eye in evaluating patterns of esthetic conformation. Scientific methods manifest their superiority when more subtle relationships are sought, such as those encountered in the dynamics of movement. It is only after attaining some degree of familiarity with the body in motion that one begins to appreciate the extent to which the proportions we measure in the body at rest owe their existence to satisfactory performance as parts of the dynamic mechanism. Certainly, the human body from the neck down is heavily indebted to the selective influence of motor performance in guiding its evolution. Even the skull has adapted to locomotor posture, and the brain it enshrines has added complexity to guide more intricate movements. Appreciation of the human being as a locomotor mechanism can be enriched by many quantitative approaches. Characterization of individuals by the speed with which they traverse distance is an example of early dynamic anthropometry. Facility in starting and stopping, a measure of the application of accelerations, is of interest to the spectator in athletics and to the individual himself when competing with traffic. Still another useful approach is through energy exchange, with measurements of oxygen consumption and heat production providing convenient data. More congenial to the physical anthropologist as a starting point for a reconnaissance of human movement is a consideration of the physical characteristics of the mechanism. With this mechanism he already has personal and professional acquaintance, and many of its components he has measured. Now he finds that their motor function can be reflected best by measurements of dif€erent design. The dimensions of skeletal elements most useful for the selection of drawers in which to keep them need not be the best gauges of their contribution to movement.