Ecsoarclies on the Discharge of the Electric Organ. ^ 



individuuls taken, in sucli a numner that the variation appears to 

 occur in accordance witli the law of errors. Since now the tissues 

 of an organism consist of a large numher of structural elements, it 

 is natui-al to suppose that a characteristic helonging to these ele- 

 ments varies in different individuals according to a similar law. 

 Then, it may be remarked, that the treatment of the physical 

 phenomenon in a tissue must l)e based on the principle of prob- 

 ability, and especially in the treatment from the standpoint of the 

 ''all or none "* theory, the application of this principle must be 

 effective and indispensable, for a physical phenomenon exhibited 

 by a tissue must be the integral effect of the phenomena occurring 

 in each of the component elements. 



II. Description of the Fish, and Preparation 

 of the Organ. 



The structure of the electric organ in Astrajx' jajwiiica was 

 recently described in detail by K. Ishimori +, and therefore need 

 not be entered into here. However, a few points having direct 

 bearing on the present investigations may here be recorded. 



The external asj^ect of the fish and its electric organs are re- 

 presented in Plate I. The length of the mature fish is al)Out 25 cm., 



* Lucas inferred from his investigation on the contraction of a skeletal muscle, M. 

 cutaneus dorsi, of the frog (Journal of Physiology, Vol. 38, 1909.), that, when a stimulus 

 greater than a certain threshold value is given to a single nerve-fibre, the excitation evoked 

 in it appears to have a definite value independent of the intensity of the stimulus. Then, 

 it seems very probable that, with regard not only to a nerve but to tissues in general, tlie 

 excitation evoked at a point in the excititory eleuients follows the so-called "all or none" law. 

 In other words, there exist only two alternatives, i.e., whether the excitation does occur in a 

 definite intensity or not at all,— no intermediate value being i>ossible. In this view, the 

 liropagation of the excitation should take placj by the successive action of the excited 

 point towards its neighbour, the projiagation in reverse direction being impossible in 

 virtue of the existence of the refractory period. The energy of the excitation of each, portion 

 should be supplied by some chemical change in it, and therefore its intensity should 

 depend on the physiological state of that portion only. A case may occur, that an excita- 

 tion is enfeebled on its way to pro^^agation, by passing through a portion in an abnormal 

 state, to such a degree as is incapable of evoking the excitation of the neighbouring portion. 

 Then the farther propagation is impossible and stops there. For proper understanding of 

 the discussions throughout this pajjer, it is necessary t? keep these considerations in mind. 



t Beitrage zur Pliysiologie. Festschrift zu Ehren der 25 Jihrigen Lehrtätigkeit von 

 Kenji Osawa. 



