Note sur la vitesse de propagation de l'agent nerveux dans la nerfs rachidiens; (Transmise par M. de Humboldt). (Séance du Lundi 25 Fevrier 1850). (+) Deuxieme Note sur la vitesse de l'agent nerveux. (2 Papers).

Paris, Bachelier, 1850 a. 1851. 4to. No wrappers. In: "Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences", Tome 30, No 8 and Tome 33, No 9. Pp. (185-) 215 a. pp. (253-) 276. Helmholtz's papers: pp. 204-206 a. pp. 262-265. Clean and fine.

First appearance (also in Berichte königl. Preuss. Ak. the same year) of these short notes in which Helmholtz announced his discovery and measurements of the time delay of nervous impulses, a discovery "which opened a new and unbounded field of investigations to physiologists". It is one the most importent discoveries in physiology in the 19th century.

"Du Bois-Reymond... received Helmholtz's first two-page note. Müller, to whom Du Bois tried to ecplain it, insisted on rejecting the conclusion, arguing that Helmholtz had not eliminated the time for the contraction of the muscle. Humboldt, du Bois wrote Helmholtz, "war ganz depaysiert", and at first refused to send the paper to Paris for publication there. Du Bois had first to edit it and then Humboldt, won over, had it published in the "Comptes Rendus", adding a further explanatory foot-note of his own. By summer, Müller had also been won, and then helmholtz published his longer paper in which he included a measurement of tghe time of the muscular cobntraction and nes determinations of the rate of transmission."(Boring "History of Experimental Psychology", p. 48).

"To separate the movement in time from the event of will that caused it was in a sense to separate the body from the mind, and almost from the personality or self. At any rate, helmholtz's discovery was a step in the analysis of bodily motionthat changed it from an instantaneous occurrence to a temporal series of events, and it thus contributed to the materialistic view of the psychophysical organuismthat was the essence of nineteenthy century science.... The most impiortent effect of the experiment and all the research that followed upon it was, however, thatit brought the soul to time, as it were, measured what had been ineffable, actually captured the essential agent of mind in the toils of natural science." (Boring "History of Experimental Psychology", p. 42).

"Helmholtz’ research in sensory physiology began in 1850, when he determined the velocity of the nerve impulse in the sciatic nerve of the frog. In 1852 he obtained more precise results through his invention of the myograph. This device, in which the muscle traces the motion of its contraction upon a rotating drum, permitted more exact measurement of the small time intervals involved than any previous method. Helmholtz’ measurements yielded not only a finite velocity for nerve propagation but also the surprisingly slow one of about ninety feet per second. The result was considered a victory for the mechanistic school, for it seemed to confirm du Bois-Reymond’s hypothesis that the nerve impulse consisted in the progressive rearrangement of ponderable molecules."(DSB).

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