^^^^^ Bovard: Giant Fibers in Earthworms 137 



MATERIALS AND METHODS 



Material. — Both the common Allolohophora foetida and Helodrilus 

 caliginosa were used in these experiments. Similar results were ob- 

 tained with each, but in general the larger worm was the easier to 

 work with, especially when operations were made for the removal of 

 sections of cord. 



Methods. — In all cases where operations were to be performed the 

 worms were kept for at least twenty-four hours in clean moist cloths, 

 so they would clear themselves of dirt and grit. "Worms that were 

 kept in moist filter paper usually ate large quantities of this, which 

 made the cutting of sections quite difficult. 



The transecting of the nerve cord was a simple operation. The 

 worm was held tightly on a moist surface and a transverse cut made 

 with a safety razor blade. A single stroke was usually sufficient to 

 cut both ventral muscle and the nerve, and if care were exercised 

 there was little danger of cutting too deep. The cut was examined 

 with a hand-lens to make certain that the cord had been cut. 



A simple physiological method of determining whether the cord 

 had been sectioned, and a method that proved a check on all experi- 

 ments, was as follows: Examination of the worm immediately after 

 the operation showed that the muscles posterior to the cut had lost 

 their tone, giving an increase in the diameter of the part. This con- 

 dition did not extend for any great distance, but was usually confined 

 to from three to five segments. If the nerve had not been severed, 

 this effect wore off after the first day of regeneration; otherwise it 

 remained enlarged until physiological continuity was re-established. 



In operating on Helodrilus, a simple transverse cut with a razor 

 blade usually only severed the musculature. The cord adheres very 

 closely to the intestine and comes away from its ventral muscles very 

 readily. In these cases it was necessary to cut the cord with a pair 

 of fine scissors, making a simple snip. Where care was not used and 

 the ventral blood vessels were cut also, the animal bled profusely, and 

 in many cases died or autotomized the posterior piece. 



When necessary to remove two ganglia, the worms were anesthet- 

 ized in a 5 per cent alcohol solution for fifteen minutes to one-half 

 hour, in all cases until they were motionless. Under a dissecting 

 microscope, a transverse cut was made in the ventral muscles. The 

 opening was stretched and pinned back with clean, fine needles. The 

 nerve cord and bloodvessels then could be easily seen. Great care 



