MUSCLES, NERVES, AND ELECTRICAL ORGANS. 205 



pads, covered with films of albumen, even to root-bundles of 

 smaller animals. Though not absolutely necessary, it is very 

 much to be desired that the experimenter in these researches 

 should be able to give his undivided attention to the manipula- 

 tion of the apparatus, and that he should be relieved of the 

 trouble of preparation. Here again I remember, with heartfelt 

 thanks, Pfliiger's self-sacrificing assistance. During many a July 

 afternoon in the tropical summer of 1857, while I kept everything 

 in readiness at the nerve-multiplier, he prepared bundles, first 

 of anterior and then of posterior roots, which, as it must be done 

 as quickly as possible without pinching or displacing the roots, is 

 not so easy as might perhaps be imagined. 



In these experiments the battery consisted of only a few Groves ; 

 the time of closure amounted to about o"'2. Any nerve-current 

 present was compensated by means of a primitive arrangement, out 

 of which the round compensator was subsequently developed *. The 

 roots were placed, along with the four wedge-shaped pads, on a 

 small support, the ' root carrier/ which could be rotated on a per- 

 pendicular axis. This allowed them to be reversed between the 

 'conducting vessels 2 ' without risk of displacing them on the pads. 

 The object of this was to obviate as much as possible the electrical 

 inequalities of these vessels and any irreciprocity of conduction in 

 the circuit (Sect. 10). The current was sent through the roots 

 alternately, first in one direction and then in the other, the direc- 

 tion being changed every minute and a half. After every four 

 experiments the roots were turned round. Such series as the 

 following were thus obtained: 



THREE GROVES. TIME OP CLOSURE ABOUT o"-2. 

 Motor Roots. 



|f_iotr-i3 |f-ii tf-i3 

 1 1 + 16 j 1 + 10-5 l 1 + 16.5 | 1 + 10 



H 



Hoots reversed. 



-12 Ij-ii T r_i 2 |r_i 2 

 + 12-511 + 11.5 j 1+1311 + 13' 



Roots reversed. 

 jr_ I2 jr_ I3 |r_ I4 jr-ia. 



|1 + I2 | 1+12-5 jl + I2 |1+I2 



Sensory Roots. 



t;-"ir-i7 TJ-II 1 1-17-5. 



I l-H4il + I2.5 j 1 + I311+ 



I2 



1 Gesammelte Abhandlungen, vol. i. pp. 176, 177. 



2 [Du Bois' < Zuleitungsgefasse,' not BO familiar now as formerly. ED.] 



