The expenditure per km. an hour for a person weighing 70 kilos was -

In racing a distance of over 100 metres in twelve seconds the work done amounted to 7,230 kgm. a minute.

By the help of mechanical devices one may travel a distance with much less expenditure than by using only one's own motor apparatus. A comparison of the expenditure of the above individual in walking and in cycling was as follows : -

If the road ascends, the expenditure of force in cycling increases greatly. If the weight of the cycle and the rider together is 90 kg., in travelling 15 km. an hour on the horizontal little more than 2,960 kgm. of work is done. In a 3 per cent, rise, e.g., 30 metres rise per kilometre, the expenditure is increased by 30 X 90 = 2,700 kgm., and the work is therefore nearly doubled.

From what has been said on food, force production, and force consumption within the organism the importance of physical exercise in anomalies of nutrition is obvious. Over-nutrition, when we take in more than we use and increase in weight, nutritive equilibrium, where our intake and expenditure cover each other, and under-nutrition, when our expenditure rises above our intake and we become thin, are all relative terms, which, irrespective of food supply, are chiefly determined by our movements. Just as rest plays a great part in the treatment of thin patients who are below their normal weight, so exercise plays an important part in the treatment of obesity. A great prophylactic influence has for long been ascribed to exercise in regard to gout and diabetes, and it is believed to have a great therapeutic value in the treatment of these still somewhat mysterious dystrophies.

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In discussing the influence of gymnastics on the nervous system, as in all else, I assume the reader's knowledge of the anatomical conditions connected with it. But with regard to the study of neurons worked out by Waldeyer, Forel, His, and others, whose opinions vary markedly in detail, but agree fairly well in the main, I consider it my duty to put forward here the various opinions of modern anatomists. It is also suitable to mention briefly the connection between the various parts of -the nervous system.

I will remind you first of the arrangement of the motor and sensory neurons in the cerebro-spinal nervous system.

If we follow one of the numerous motor neurons from its ganglion cell anywhere in the cortex of the cerebrum to its muscle end-plate, which finally gives up to the muscle the impulse which it was carrying from the said ganglion cell, we meet on the way at least two of the anatomical units, consisting of ganglion cell, nerve fibre and end apparatus, which form the modern histologist's neuron. The central of these two neurons begins with an automatic motor voluntary ganglion cell in the cerebral cortex, goes thence through the pyramids, in such a manner that the non-decussated fibres go by the anterior longitudinal fissure via the anterior pyramidal tract, while the decussated fibres travel in the lateral (pyramidal tracts) columns of the cord to a ganglion cell in the grey matter of the cord. The central neuron ends in the immediate vicinity of the dendrites of this ganglion cell, from which the impulse travels across in some unknown manner to the peripheral neuron, though it must be noted that structurally the neurons are, as everywhere, distinct from one another.

The latter (peripheral) neuron begins in the above-mentioned ganglion cell, passes as a nerve fibre in the anterior column of the spinal cord, and through one of the anterior nerve roots out of the cord (accompanied by other centrifugal (motor, secretory, and vaso-motor) nerve fibres) to some skeletal muscle, and ends there in a muscle "end-plate."

The sensory, centripetal paths are more complicated, and much still remains to be discovered before we can really claim to understand them. In discussing them I follow to a large extent the diagrammatic plates given us by Mott (p. 288 in L. Hermann's latest edition). We begin then to follow the nerve path from the periphery, and from one of its end apparatus in the skin, in a tendon, muscle, or joint capsule (from a tactile corpuscle or a Pacinian body). The sensory fibre passes in a spinal nerve towards a spinal ganglion, from one of the ganglion cells of which it originates in the following manner. Each ganglion cell gives off only one process, an axon which very soon divides in a T-shaped manner to give two branches, one of which is the sensory fibre coming from the periphery, while the other passes into the spinal cord by way of the posterior or dorsal nerve root, and then runs upwards in the posterior columns of the spinal cord, either in its medial (Coil's) fasciculus (= funiculus gracilis) or in the lateral (Burdach's) fasciculus (= funiculus cuneatus). On its course it gives off collateral branches, some of which communicate indirectly with the motor ganglion cells in the anterior horn of the cord by means of an intermediate neuron. One of the collateral branches of the ascending division ascends in the posterior part of the cord to a ganglion cell in Clarke's column, from which axons arise which ascend still further in the direct cerebellar tract in the lateral column to the cerebellum and arborises round a Purkinje's ganglion cell. It is to be remarked that this cell sends out a centrifugal neuron, which by means of an intermediary neuron is connected with a motor ganglion cell in the anterior horn of the cord.

- But the fibre spoken of above as coming out from the spinal ganglion cells gives off a still longer branch, which ascends in Coil's or Burdach's fasciculus of the posterior column of the cord and reaches a neuron cell in the medulla (in the nucleus of the funiculus gracilis and cuncatus). This ganglion cell belongs to an intermediary ascending neuron. From it a crossing nerve fibre goes up to the optic thalamus and there arborises round a ganglion cell in this important collection of grey cerebral substance (i.e., of ganglion cells). From this last-mentioned ganglion cell goes a third nerve fibre (reckoned from below) to some nerve cell in the cortex of the brain.