Paul Bert

“ PHYSIOLOGISTS are as yet by no means agreed whether the nerves which, from their special functions, have been termed motor and sensor nerves, are in their essential properties identical or different; in other words, whether a sensor nerve can transmit excitations whose result is motion, and vice versa. We do not even know whether an excitation produced midway in the length of a nerve is simultaneously propagated in both directions, centrifugally and centripetally. ”

“ By little and little the rat is educated, and at last recognizes the exact point that is excited; thus showing that our so-called innate knowledge of the place occupied in space by every point of our bodies is, like all our knowledge, merely the result of repeated experiences.
To conclude, the experiment I have just recounted shows that excitation of a sensor nerve at any point of its length is propagated in two directions, both centrifugally and centripetally. The same is doubtless true of a motor nerve. ”

“ Oxygen, which gives us life, slays also, when administered in too strong a dose. I have had to study thoroughly this paradoxal poison to determine the different effects of varying doses, and its action upon our tissues. ”

“ But if he stirs about, if he tries to lift the weight of his body by climbing, then he has need of more oxygen than is contained in the blood; and, as this is not to be had, the symptoms of mountain-sickness make their appearance, and the only hope of relief is in repose. This is the reason why aeronauts, who perform no work, experience "balloon-sickness" at a far greater elevation than mountain-climbers experience the symptoms to which they are liable. ”

“ These terrible symptoms are not the result of compression, as I have been able to prove by two experiments. In the first place, they can be produced at the pressure of five atmospheres, provided pure oxygen be used instead of air, which latter has no special effect at this pressure. Secondly, they do not make their appearance if the air subjected to twenty atmospheres' pressure is very poor in oxygen.
Thus it is the oxygen that is to blame. Oxygen at too high a degree of tension destroys animal life. ”

“ THE great influence that may be exerted upon living beings by atmospheric pressure is now questioned by none, and there is even a disposition to exaggerate its importance. If the barometric column rises or falls a few millimetres, nervous people affected with the asthma perceive phenomena, whether of a beneficial or of a noxious kind, which they do not hesitate to attribute to the weight or to the lightness of the atmosphere. ”

“ Oxygen at a high tension kills not only the higher animals: it acts alike on vertebrates and invertebrates, animals aerial and aquatic, plants and animals, big and little, even microscopic organisms. Its effects upon the latter are highly interesting.
From the admirable researches of Pasteur it appears that the phenomena of fermentation are of two kinds. One set of phenomena are correlated with the development of microscopic organisms ”

“ The experiments made in the cylinders demonstrate, beyond the possibility of doubt, that these symptoms depend solely on the tension of the oxygen in the air respired; an aëronaut breathing common air (21 per cent. oxygen) at one-half common atmospheric pressure is precisely in the same condition as a man who, at normal pressure, breathes air that holds only one-half the normal proportion of oxygen. Consequently, he is subject to conditions of insufficient oxidation, and threatened with asphyxia. Hence his rapid respiration, in the effort to introduce into the blood the oxygen which is lacking ”

“ If we pinch a sensor nerve at any point of its length, the pain that is felt clearly shows that the excitation is propagated in the centripetal direction; but of a centrifugal propagation we know nothing, for the very simple reason that at the terminal extremity of the nerve there is no nervous apparatus of perception. ”

“ Among the many theories more or less tenable a priori, but none of which will stand the test of experiment, there is one which is almost universally accepted, and which reckons De Saussure among its distinguished supporters. It is known that the atmospheric pressure on a square centimetre of surface is 1.03 kilogramme. If we multiply this by the number of square centimetres of surface in a man's body, the product is something enormous. Take an average case, a pressure of say 15,000 kilogrammes. We are in equilibrium with this great pressure, they say ”

“ The greatest height attained by man was reached by Glaisher in a balloon—8,840 metres, pressure 24. 76 centimetres—and by the brothers Schlagintweit on foot, in the Himalaya, 6,882 metres, pressure 32 centimetres. The highest mountain on the globe, Gaurisankar, measures precisely 8,840 metres—the elevation at which Mr. Glaisher fell fainting to the floor of his car.
Such modifications of pressure cannot be endured with impunity by the human organism. ”

“ When they first appear, a few moments' rest suftices to banish them; this instantaneous restoration of strength and vigor sharply distinguishes mountain-sickness from ordinary fatigue. But at greater elevations, where graver symptoms appear, such as bleeding from the nose or from the lungs, repose cannot bring back the condition of perfect health, though it always afibrds some relief. Travelers agree in saying that a person on horseback suffers far less than one on foot. ”

“ On the high plains of the northern Himalaya, a rather brisk pace in walking, the ascent of a hill however low, the carrying of a moderately heavy load, sufiice to exhaust one's strength, to cause him to faint, and in some cases even to produce death. ”

“ As the soil is removed, the tube descends by its own weight; it is lengthened by the addition of successive sections, till the solid rock is reached. The cylinder is now filled with béton and the pier is complete.
In these apparatus workmen have also been subjected to pressures as high as five atmospheres.
Now, both among divers and workmen in these tubes, symptoms have been noted often so serious as to terminate fatally. First there is an intolerable itching, called by the workmen "the fleas" (puces) ; then violent pains in the muscles and joints which have done most work ”

“ I once hoped to be able in this way to preserve meats, eggs, etc., but this was an illusion. The substances do not become putrid, but, in consequence of a pseudo-fermentation, which sours them, they acquire a disagreeable taste, which takes from the process all its industrial value. ”

“ The admirable experiments made by Philipeaux and Vulpian to determine these knotty questions are, as Vulpian was the first to observe, susceptible of a different interpretation from that unanimously put upon them by the world of science. ”

“ I remove, for the length of two or three centimetres, the skin from the tip of a young rat's tail, and insert the flayed part into the subcutaneous cellular tissue through an opening made in the skin of the animal's back. A few stitches suffice to hold the parts in place, and soon they adhere firmly, the rat's tail then having the ansate form. ”