REGENERATION IN ANNELID NERVE CORD 165 
as a cork, under a binocular microscope. A small obliquely 
transverse slit is cut in the epidermis, a few metameres posterior 
to the clitellum. Then with a needle sharpened to a knife 
edge on one side, the nerve cord is picked up and cut.. Care 
must be taken not to sever the ventral blood-vessel, as too 
severe bleeding is injurious. The worm is then replaced in the 
moist cloths. 
When removing several segments of the cord, a transverse 
slit is cut in the ventral epidermis as before, and then the skin is 
carefully lifted up with the point of the scissors and cut longi- 
tudinally for several segments. When placed under the binoc- 
ular, the nerve is seen lying in the furrow made by the cut. 
The sharpened needle is inserted and the cord cut. One can 
then count down as many segments as he wishes, insert the 
needle and cut again. The section of cord is removed with the 
forceps and dropped into alcohol, which causes the ganglia to 
form contraction knots. These may be counted as a check on 
the number of segments removed. The skin wound usually 
closes in from two to four hours. The jars and cloths in which 
the worms are kept are thoroughly cleaned with hot water each 
day to prevent infection. 
B. Technique 
In order to study the process of regeneration, a large number 
of worms were operated on and then killed at intervals of fifteen 
minutes for the first six and a half hours. This series was 
stained by the Hardesty method no. 1, which gives good fiber 
differentiation and is supposed to show mitosis, if any be present. 
Erythrosin and toluidin blue were the stains used. Although 
cellular and intercellular structures are clearly contrasted by 
this method, the killing agent used is a poor one where delicate 
scar tissue is involved, as the violent action of the absolute 
alcohol tends to pull the cicatrix loose from the wound on one or 
both sides. Another series gives fifteen-minute intervals of 
regeneration, up to an hour and ten minutes, then for periods of 
several hours up to four days. This series was killed in Perenyi’s 
fluid and stained with iron haematoxylin and orange G. 
