( 148 ) 



after its being' transfen-ed to llic iioi-vc. That it is not tlie intensity- 

 factor before the transfer which must be regarded liere as the [)liy- 

 siologically "auslösende" (liberating) force, appeai-s from some curious 

 results obtained on varying the height of fall. A fall of 5 mm. 

 gives an excellent lifting distance when the muscle is loaded with 

 50 grams, which is reduced to "/., with a fall of Jo mm. and to \/j 

 with a fall of 30 mm. Consequently a smaller effect is found when 

 the velocity with which the drop comes down is increased, instead of 

 a larger effect. This would be impossible if the intensity-fact(tr of the 

 kinetic energy of the falling drops had been decisive. On diniiiiishiug 

 the height of fall agaiji the original lifting distance returns'). 



The second kind of artificial stimuli cau be measured in a very 

 simple manner if at the instance of Cvi51i-skv, Mai{Ks, HooHWiui and 

 others, condensers are used. A pielimiuary trial in the laboi-atory 

 showed that the best results are oblaine<l with a condenser of a 

 capacity of 0.004 microfarad. This has only to be charged to a 

 potential of 0.012 \olts to show already a conli'action of the Jierve- 

 miiscle preparatio]!. The available energy in this case amoimts to 

 0.00029 ergs, which i^ much less than what was found for mecha- 

 nical stinndation 'j 



But it is clear that the one as well as the olhei' i> a most unsatis- 

 factory way of stimulating. The mechanical slinniiiis only i-eaclies 

 part of the axial cylin<lers consliluting the nerNe-biindle and it is 

 questionable whether the softness of the mass does not to a great 

 extent obviate the suddenness of the pressure. The electrical discharge, 

 although more instantaneous, s|)reads in no small measure, besides 

 over the axial cylinders, also oxer the sheaths and the septa between 

 the separate fibres. A means of diminishing the resistance and so 

 making the time of discharge shorter is hitherto lacking. It is always 

 the full resistance of the nerve, measured across, which one is obliged 

 to ])ut in. 



These difliculties will never be completely overcome with artificial 

 stimuli; in order to find the real minimum one must have recourse 

 to natural stimuli. It is oidy with sensory nerves that we have these 

 at our conunand for the present. 



There are two organs of sense in which the nerve-cells themselves 

 (or their immediate prolongations) receive the stimulus, viz. the 

 organs of sight and of smell. In the former case it is the rods and 



1) An analuguub phtjnumeiioii has been observetl by Wede.xsky for laradic 

 stimuli (of a freiiuence of lüO per second). 



~) J. Cluzet. Journal de Physiologie et de Pathologie générale 1904 p. 210 gives 

 as smallest values 8, 5 and 7, 2 milli-ergs. 



