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University of California Publications in Zoology [Vol. 18 



results were obtained than where the nerve was allowed to come in 

 contact with the cork of the dissecting tray. Garrey and Moore (1916) 

 used a method similar to the earlier method that I used with the same 

 general results. 



(&) Graphic Records. Apparatus. As a check on the observations 

 just described, it became desirable to find some way in which to make 

 a graphic record showing the part the nerve cord plays in the trans- 

 mission of locomotor impulses. The movements of the anterior and 

 posterior ends of the worm, while the middle part was fixed to a cork 

 plate glued on glass, suggested that if levers were attached to these 

 moving parts a record could be obtained on a kymograph. It was 

 necessary in order to obtain good records to have the levers as light 

 as possible and to have them move wdth very little friction. This w^as 

 accomplished by making the levers of aluminum wire, number 22. A 

 desired length was inserted in a cube of cork. Through the cork a 

 small glass capillary tube was thrust which made the bearing for the 

 axle of the lever. A very fine needle was then fitted into the glass 

 capillary and the needle stuck into a firm support. This sort of a 

 bearing allowed the lever to move with little friction and also was 



Fig. 5. The general arrangement of the apparatus for recording movements 

 of the anterior and posterior parts of the worms. Method used at Harvard, 

 1914-1915. 



a.l. — Aluminum wire lever connected to anterior end of worm by hook and 

 thread; c. — Cork plate gkied to glass for pinning the middle anesthetized por- 

 tion; c.c. — Cork cubes through which aluminum wires run; g.pl. — Glass plate to 

 which a little water was added to allow the worm to slide back and forth when 

 pinned; p.l. — Aluminum wire lever connected to posterior end of worm b}' hook 

 and thread; Tcy. — Drum of kymograph for taking tracings on smoked paper; 

 wt. — Counter balance weights. 



