206 HANSFORD MACCTJRDY 



the limits of the experiments. Three individuals in which the 

 fifth ganglion had been isolated were not killed until ninety days 

 after the operation. These three presented a condition of the 

 ganglia and ganglion cells very similar to that found in ganglia 

 at the end of thirty-nine days. The parts , of the ganglion 

 which had undergone degeneration were somewhat more clearly 

 distinguished from the remaining portion. There was some evi- 

 dence that partial regeneration had occurred in these ganglia, 

 but this was not conclusive. 



THE FOURTH AND THE SIXTH ABDOMINAL GANGLIA 



In these experiments, as already stated, the connective between 

 the fourth and fifth abdominal ganglia was severed a few milli- 

 meters posterior to the fourth ganglion ; some cells in this ganglion 

 might, therefore, be expected to degenerate. In all cases the 

 fourth ganglion was prepared in the same manner as the fifth 

 and this included the posterior end of the connective. An examina- 

 tion of these ganglia revealed degenerating cells in their anterior 

 parts on both right and left sides, and a few cells in their middle 

 portions on each side near the ventral surface. These were most 

 clearly seen twenty to thirty days after the connective had been 

 severed. In these cases the nerve cells in the posterior part of 

 the ganglion were but little influenced. In certain cases of longer 

 standing some of these posterior cells suffered partial degenera- 

 tion. 



The sixth abdominal ganglion was prepared in the same way 

 as the fourth and fifth. Degeneration of a considerable number 

 of nerve cells in the anterior parts of this ganglion was found in 

 all cases twenty or more days after the connective had been severed. 

 A smaller number of nerve cells in a similar condition of disinte- 

 gration were found near the ventral surface in the sections through 

 the middle and posterior portions of the ganglion. The beginning 

 of degeneration in this ganglion was found in preparations made 

 twelve to fourteen days after the operation. 



The degenerating ends of the connectives were included in the 

 preparations and mounted in series with the related ganglion. 



