138 University of California PuUications in Zoology [Vol. 18 



had to be exercised to prevent cutting any blood vessels. The cord 

 was lifted up with fine forceps, and a cut made anteriorly. The cord 

 could then be pulled forwards and a cut made posteriorly. The seg- 

 ment, which was removed, was then put into 95 per cent alcohol and 

 examined later to ascertain the exact amount of nerve substance re- 

 moved. 



After the operation the worms were placed in small 8-ounce jars 

 with some moist cloths over them and put away in a dark cabinet. 

 It was not found necessary to keep the worms in a particularly cool 

 place as long as the jars and cloths were kept scrupulously clean. The 

 temperature was the ordinary room temperature during April and 

 May in the Harvard laboratories. The only cases where worms died 

 during these experiments were those which bled profusely after the 

 operation due to rupture of the large ventral blood vessel. The loss 

 was surprisingly small. 



By the following day the worms appeared normal, the wound had 

 healed over and they could be seen creeping about in the jars. Usually, 

 however, they were not very active in the cramped quarters of their 

 jars. 



Effect of Transverse Sections of the Cord 



The result of simply transecting the cord was the loss of trans- 

 mission and of the animal's power to reverse its direction of creeping 

 on stimulation. Stimuli applied at either end ran as far as the cut, 

 but failed to pass across the break in the cord. Earthworms often 

 respond to strong stimuli given to the anterior end by certain lashing 

 movements and side to side jerks. When the cord was severed these 

 lashing movements could be induced in the anterior portion of the 

 worm without producing any effect on the posterior part behind the 

 cut, which might lie quiet during this movement. Giant fiber action 

 induced either from the anterior or the posterior direction was effective 

 as far as the cut only. The quick, end to end action never succeeded 

 in starting the same kind of a movement in the portion of the worm 

 on the other side of the break opposite to the point stimulated. 



The effects on the musculature were particularly noticeable. Im- 

 mediately behind the cut region the worm showed an enlargement of 

 the segments. Here the circular muscles seemed to have lost their 

 tone. As the worm crept along the posterior part acted in co-ordi- 

 nation with the anterior, but these few segments behind the cut took 

 no part. The length of this inactive part varies from three to five 



