Electro-physiology (1896-98) Electro-physiology electrophysiolog01bied Year: 1896-98 IV ELECTROMOTIVE ACTION IX MUSCLE 367 segment (the hatched part of the curve, Pig. 114) is therefore always cut out of the superficies of a variation curve, and through its summation a deflection of definite proportions is produced. And, since the time of galvanometer closure can be prolonged as required over the entire interval between the two stimuli, the form and magnitude of the curve of variation corre- sponding to each single stimulus are easily determined. The credit of having constructed apparatus tha
Electro-physiology (1896-98) Electro-physiology electrophysiolog01bied Year: 1896-98 IV ELECTROMOTIVE ACTION IX MUSCLE 367 segment (the hatched part of the curve, Pig. 114) is therefore always cut out of the superficies of a variation curve, and through its summation a deflection of definite proportions is produced. And, since the time of galvanometer closure can be prolonged as required over the entire interval between the two stimuli, the form and magnitude of the curve of variation corre- sponding to each single stimulus are easily determined. The credit of having constructed apparatus that satisfied these require- ments belongs to Bernstein (20), whose 'differential rheotome ' has since found an extended application in experimental physio- logy. The instrument consists essentially of a wheel (/•) (Fig. 115) FIG. 114. revolving easily round the central axis, worked as uniformly as possible (5-10 revolutions per second) by clockwork, or a small motor. At the periphery of the wheel there are three isolated metal-points (according to Hermann, brushes of copper-wire), one of which (c) forms the exciting contact, the other two (</, c') effect the closure of the galvanometer circuit. The former slides at each revolution over a thin extended wire, or pool of mercury, and thus closes the circuit (R\ li') of the primary coil of an induction apparatus. The currents produced in rapid succession in the secondary coil (make and break shock) are led into the prepara- tion, and may be regarded collectively as a momentary stimulus. Diametrically opposite to the exciting contacts, isolated from the
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