apply the -ame needle electrode- t< . the mu-cle directly. I- the 

 threshold value for muscle ( or the nerve fibers in muscle \ the same? 

 I 'eterniine the thrc-hold value f r different points along the nerve. 

 I- there any dift'ereiice ? I Alii >\\ ance mu-t he made in this experi- 

 ment l"r differences in the electrical resistance of the two tissue-. 

 or of the different regions of the nerve.) 



_'uS. Summation of snhminimal stimuli. t'-ing the la-t uerve- 

 mu-cle preparation, place the coils of the inductorium just far 

 enough a]>art to prevent contraction on stimulation of the muscle 

 with needle elect n>de-. Allow the muscle to rest a few minute-. 

 Xow stimulate. If in contraction results keep stimulating about 

 twice a -eomd. Doe- the muscle eventually contract? Does it con- 

 tract with a tetanizing current? Does your result indicate that the 

 excitation> outlast the stimulus and reinforce subsequent stimuli? 



209. The excitation i^\rce remains in the muscle or nen-e 

 fiber in 'leliich it starts. In order to limit the stimulus to one or two 

 filters, the method of unipolar stimulation may lie adopted. Fasten 

 in one | ii ist lit the sec< ndary coil of the inductorium arranged for 

 tetanizing currents a wire soldered to a blunt needle. F.xpose the 

 sacral plexus in a brainless and spineless frog in which the skin 

 has been removed from the hind limbs. Connect the preparation by 

 means of a copper wire to the earth through the gas or water pipes 

 by connecting with the desk binding p< sts. Touch the sacral nerves 

 here and there with the needle electrode, watching meanwhile the 

 sart<irius muscle. Do all fillers contract? Stimulate the sartoriu- 

 directly. Do only the libers touched by the needle contract? 



_'io. The same ner:-e fiber ma\ conduct impulses both ccntri- 

 petally anil ccntrif in/ally, a. The nerve of the sartorius divide- at 

 the muscle, part going to each half of the muscle. Microscopical 

 c animation sh \\--, that the division is not -imply a parting of 

 individual nerve filters, but that each axis cylinder tork-. one limb 

 going upward-, the other downward-. If the mu-cle i- -evered 

 between the fork-, no impul-e started in one halt - t the mu-cle 

 could reach the other half, except by going up one branch to the 

 original axis cylinder and down the remaining branch; for it has 

 been -howii that the nerve impulse does not escape transversely 

 in -m "lie axis cylinder to other neighboring ones. 



Keinovc a -artoHu- mu-cle with great care. Split the mu-cle 

 in the middle line for one-third of its length, beginning at the 

 bn-.ad end. Stimulate the right -egment by snipping it with a pair 

 of scissors. Xote can-fully if the liber- of the left -egment contract. 





