File:General physiology of muscles and nerves (1881) (14754714796).jpg

Identifier: generalphysiolo00rose (find matches)
Title: General physiology of muscles and nerves
Year: 1881 (1880s)
Authors: Rosenthal, I. (Isidor), 1836-1915
Subjects: Physiology Muscles Nerves
Publisher: New York, D. Appleton and company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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the apparatus K passes through thewire arranged between g and f to the primary coil c, fromthis to the coils round the small electro-magnet h, and fromthe latter through the column a, back to its original startingpoint. The electro-magnet attracts the hammer h, in con-sequence of which a small platinum plate fastened belowthe German silver spring is brought into contact with theplatinum point of the screw/, thus completing a brief andefficient additional closm-e g^f^ a. The consequence of this NOTES AND ADDITIONS. 307 is that the curreut in the coil c, and at the same time in theelectro-magntit; is much weakened; the latter can no longerattract the hammer, which springs upward, so that the plateis removed from the point / and the additional closure isinterrupted. The current once more passes in full strengththrough the coil c and the electro-magnet b, the hammer isagain attracted, and the whole process is repeated as long asthe circuit K endures. If it is required to restore the appa-
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FlG. 74. IIeLMHOLTZs ArPAR.VTUS. ratus to its oiiginal condition, it is only necessary to removethe wire g^, and to lower the point/. 7. ACTIOX OF CUKREXTS OF SlIOUT DuRATIOX (p. 152). Either the clo.sing or opening of a continuous currentor an inductive current is used to excite the nerve. In thelatter case, however, as has already been indicated in Note 308 PHYSIOLOGY OF MUSCLES AND NERVES. 3, we liave reallj^ to do with a closing immediately suc-ceeded by an opening, for the inductive current arises andagain disappears as soon as it has reached a certain strength.This may be imitated with suitable apparatus, by closing aconstant current for a very biief time. Such a currentshock may exhibit exactly the same phenomena as does aninductive current. If its duration remains unaltered, butthe strength of the cun-ent is gradually increased, the heightof elevation at iirst increases, remains for a time at a firstmaximum, after which it again increases and reaches a secondmaximum. The expla

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