132 HODGE. [Vol. VII. 



cal condition had been induced, rather than suppose that this 

 were the normal daily procedure. 



To study recovery, then, it was arranged to stimulate a series 

 of cats, equally and for the same period, and then allow members 

 of the series to rest for different lengths of time. 



The most perfect apparatus for controlling stimulation were 

 supplied me by the physical and physiological laboratories of 

 Clark University. A Weston's direct reading ammeter, read- 

 ing from 0-15 amperes, was placed next the battery. From 

 this it was possible to read off the strength of current at any 

 moment. Next to this in the circuit was placed a resistance- 

 box with rheocord attached. This is necessary for exact work, 

 as the battery was set fresh at the beginning of each experi- 

 ment and increased in power for the first hour or so, and then 

 gradually weakened until the end of five hours, during which 

 the stimulation lasted. These variations could generally be 

 compensated for by sliding the bridge of the rheocord. 



It was decided to use twenty stimuli per second, and this rate 

 was obtained by loading the interrupting hammer attached to 

 the induction coil. To make certain that this did not jar out of 

 adjustment, I was compelled to place also in the primary circuit 

 a signal which should write its vibrations under the tracing of 

 a signal in circuit with a seconds clock. 



The same interval was adopted as for the last series, viz. forty- 

 five seconds' rest alternating with fifteen seconds' stimulation. I 

 am indebted to Dr. Lombard for the most inexpensive and ser- 

 viceable little device ever invented for the spacing of intervals. 

 A small nickel clock forms the motor part of the contrivance. It 

 must be provided with a second hand. The glass face-cover 

 and all the hands are removed, and upon the shaft of the second 

 hand is fastened an eccentric zinc disc 2|- x 3 cm. in diameter. 

 In front of the clock is held by a post, properly placed, a lever 

 of hard rubber 1 5 cm. in length ; the longer arm of the lever, 

 8 cm., is between the post and the clock, so that this end, which 

 is tipped with a small gutta-percha wheel, to reduce friction, will 

 tilt back lightly upon the eccentric. The other arm of the lever 

 carries two light copper wires tipped with platinum. The plati- 

 num tips, extending downward at right angles from the lever, 

 dip into a glass mercury-cup. Thus the motion of the eccentric 

 upon the second shaft is made to tilt the lever in and out of the 



