1918] 



Bovard: Nervous Impulses in the Earthworm 



115 



advantageous in that it allowed little side lash. Various forms of 

 levers could be built up by means of extra cork cubes and short sections 

 of aluminum wire, as in figure 5, a.l. and p.l. 



The levers had to be weighted slightly so that the worm would be 

 kept in a straight line on the glass plate or else the curves recorded 

 would be exceedingly irregular (fig. 5). 



If now a worm is prepared with the middle part anesthetized and 

 arranged to record movements, the movements of the posterior part 

 should show a perfect coordination with those of the anterior part 

 (fig. 6). 



ant. 



post. 



Fig. 6. Experiment 143. A record showing perfect coordination between 

 anterior and posterior parts with a middle area of eight segments anesthetized 

 and musculature cut away. The upper curve represents the movements of the 

 anterior end and the lower that of the posterior end. Transmission of impulses 

 mediated through the nerve cord only. 



The method of preparation of the middle portion varied. In some 

 cases the worm was treated with ether by the vial method, and then 

 triple-pinned to the cork plate. In other cases, in addition, the dorsal 

 musculature was cut away, the intestine removed, exposing the nerve 

 cord, and the lateral branches of the nerve cord transected. In still 

 other cases the musculature was cut in the middle region but not 



