Researches on the Diseharo-o of the Electric Organ. 23 



coil at tlio pi'02)er instcint after the primary cuiTent is broken and 

 then to exckidc the secondary coil from tlie oscillograph circuit. 

 Since the latent period of tlie discli arge measures about 80 x 10"* 

 sec, this change of connection may be made Avithout disturbing 

 the discharge current. Referring to the figure, A and B are two 

 springs attached to an arm of a T-shaped lever. .Vt first, the spring 

 A is in contact with A.' In this case the organ, the oscillograph 

 and the secondary of the induction coil are in a series. When the 

 knock-down lever is kicked, the spring B comes into contact with 

 7>' and then ^1 parts from A.' At the moment when B touches 

 B', the secondary coil is short circuited, and when A parts from 

 A', it is excluded from tlio oscillogram)] i circuit. 'J'hen tlie organ, 

 the oscillograph and an appropriate inductionless resistance are in 

 a series, ready to receive the response of the organ. (^ is a catcher 

 of the knock-down lever to prevent it from rebounding. The 

 mechanism here mentioned is the final form used by the author. 

 In the earlier experiments mercury contacts were employed, but 

 the trembling of the surfaces of the mercury which generally formed 

 a very complex stimulus could not ])e avoided. Next we attempt- 

 ed simply to cut the secondary current instead of short circuiting 

 the secondary coil, but the spark at the instant of breaking the 

 circuit, prevented the instantaneous decrease of the current. After 

 such experiences, the author was convinced that it is very dangerous 

 to presume on the form of the stimulus l)y theoretical considera- 

 tions only; actual experimental evidence is indispensable. Plate 

 v.. Fig. 4 is a contrivance for giving two successive momentary 

 stimuli with any desired interval of time. Two electric contacts 

 are made between the ends of the levers and the knocker of the 

 car. Usually such stimuli are given to the nerve and consequently 

 in this case the connection-changer is not necessary. The distance 

 of the two points of contacts may be adjusted from zero to 25 mm. 

 and may be read to one-tenth of a millimetre by means of a 

 vernier. 



These mechanisms are fitted into the grooves fixed on the 

 base-board of the apparatus. The grooves being provided Avith 

 millimetre-scales, their positions may be read to one-tenth of a 



