Vol. XXXVII., Art. l.-K. Fuji. 



III. Plan of Experiment. 



The diagram of the plan of the experiinent is represented in 

 Fig. 1. 



The oscillograph used by us was that designed by Duddeli 

 and made b}^ The Cambridge Scientific Instrument Company, 

 and that which is known as the high h'equency type. The period 

 of strips in an undamped state measures about ]/K)i)00 sec. By 

 means of this instrument, an alternating current having a period 50 

 times that of the strips may be photographed without an appreci- 

 able error.* As the duration of a discharge of the organ measui-es 

 about 1/100 sec, the curve obtained by this instrument may be 

 relied on for quantitative analysis. As the instrument is designed 

 for an alternating current, it has a pair of strips, one for the 

 current and the other for the apphed E. ]M. F. In our 

 experiments, when the organ was stimulated directly, only one (jf 

 them was employed, the stimulating current and the resulting 

 discharge current being made to flow through the same strip; and 

 when the stimulus was sent through the nerve-trunk, one of the 

 strips was used for the stimulus and the other for the discharge. 

 The fact that both the stimulus and the discharge may be 

 photographed upon one and the same film is very convenient for 

 accurate work. The sensitivity of the oscillograph is about 2G mm. 

 for Ol ampere, the film being at a distance of 50 cm. from it. 

 The resistance of each strip is about 8 ohms. 



The fight source Q for illuminating the oscillograph consists 

 of a hand-regulating arc lamp of 15 amperes, the image of which 

 is formed on a slit s l>y a lens L. 



The registering drum D is supported within a camera and has 

 a circumference of 50 cm. (Plate III., Fig. 1). This is revolved by a 

 small motor M of 1/30 H.P. The number of revolutions used 

 was 5-20 per. sec, accoi'ding to circumstances. A photographic 

 film was wound around the drum and kept in position by means 

 of two india-rubber rings which keep each side of the film pressed 



* Zeitschrift für Instrumenten Kunde, S. 240, Bd. 21, 1901. 



