56 ^t- 1'-^- ^^Jiî 



direct effect of the distiir])ance evoked by the fir.-^t stimukis, l)ut it 

 is the effect of the first discliarge acting as a stimulus. In this 

 view we must assume tliat the maximal disturl)ance in a nerve- 

 trunk cannot cause the maximal discharge of the organ. The 

 possibility of the fact may ho considered in several Avays. For 

 instance, some elementary portions of an end-organ, say electric 

 plates or muscle fibres, cannot l)e excited by the disturbance 

 through a nerve, on account of the enormous decrement of the 

 nerve-endings of those individuals, or else the disturl)ances in some 

 nerve-fibres are too small to l)e transmitted to the end-organ for tlie 

 same cause. In our exjieriment, when we take a i>art of an organ 

 with a nerve-trunk attached, there certainly exist electric 

 plates which do not receive the supply of the nerve-tibres from the 

 trunk through whicli stimuli are gi\'en. Such plates cannot be 

 excited by stimulating the nerve-trunk, but can be excited by 

 the discharges of the electric plates belonging to that ner\'e-trnnk. 

 Then, when the discharge of such secondary nature is super}:>osed 

 on the discharge evoked l>y the second stimulus, the result 

 must be the increase of the magnitude of the second discliarge. 

 If we may allow that the electric response of muscle may act 

 as a stimulus, then the same interpretation may be appliedi n 

 the case of nuiscle. 



Our experiments hitherto described were made in such cases 

 as the discharge evoked by the first stimulus had an asymptotic 

 values in practice. Without presuming the law of " all or none " 

 it is A'ery important to examine the case when the discharge is so- 

 called submaximal. We have three series of such experiments 

 that were obtained accidentally. These are Oscillograms No. 50, 

 No. 47 and No. 51. 



In ( )scillograni No. 50 (Plate XXL), when two stimuli separated 

 by an interval 77 5 x 10"* sec. , the response l)y the second cannot 

 be observed. When they approach CG 3x Kj^Vec. , we see a low 

 discliarge scarcely distinguishable from the secondary. Tlien they 

 approach nearer /. e. to 55 0xl0~* sec. and the second discharge ap- 

 pears on the descending branch of the first discliarge. When they 

 approach each other still nearer /. e. 29 9 x 10"* sec, the second 



