200 HANSFORD MacCURDY 



ing the lance, or a fine-pointed pair of scissors, the connective was 

 severed about midway between the fourth and the fifth ganglion. 

 Through the same incision the instrument was passed backwards 

 in a line nearly parallel to the long axis of the body, severing the 

 lateral nerves on the right side of the fifth ganglion. Another 

 incision similar to the first was made to the left of the median line 

 between the fifth and sixth sternites and through it the connective 

 between the fifth and sixth ganglion and the left lateral nerves of 

 the fifth ganglion were severed. A thin coat of celloidin was then 

 applied to the wounds. Thus the connectives, both in front of 

 and behind the fifth ganglion, and the lateral nerves on each side 

 of it were cut with the least possible amount of injury to the tis- 

 sues, and the ganglion was thus isolated as regards its nerve con- 

 nections. The animals were then numbered for purposes of identi- 

 fication, placed in an aquarium, and propery cared for until 

 they were taken for study. Only those animlals in which the 

 wounds healed readily and which showed no evidence of infection, 

 etc., were selected for final preparation and study. 



At desired intervals after the operation, individual animals 

 were killed, and the abdominal ganglia from the third to the sixth 

 inclusive were removed together by cutting along the ventral 

 surface through the integument and sternites on each side of the 

 median line, and carefully removing the ventral wall of the body 

 with the nerves and ganglia in situ. The entire piece was kept 

 straight by attaching it to a glass rod and in this position it was 

 immersed at once in the killing fluid. Before clearing, the nerve 

 elements were carefully removed from their natural position on 

 the body wall and transferred together through absolute alcohol 

 and xylol and imbedded in paraffin. 



Since the cells of the isolated and the normal ganglia were 

 finally to be carefully compared, it was necessary to give them, 

 as nearly as possible, the same treatment. To secure this equality, 

 one normal individual and one individual which had been operated 

 on, were killed and prepared together in the manner described 

 and given parallel treatment throughout. 



Two methods of treatment were used. One series was prepared 

 according to the Nissl method for staining the tigroid substance, 



