EXPERIMENTS ON ASCIDIANS 45 



much sooner than a normal animal. Hence the 

 nervous system does not contain any regulating me- 

 chanisms, but it serves as a quicker conductor, and 

 allows the peripheral organs to work with greater 

 precision. 



4. Bethe has recently made a difficult experiment 

 on Carcinus mcenas, which, however, was successful 

 in only two cases. If this experiment is correct, it 

 proves that, in the conduction of a reflex in the cent- 

 ral nervous system, the process of conduction does 

 not of necessity pass through the ganglion-cell itself 

 (5). An anatomical observation caused Bethe to 

 perform this operation. " Almost all the ganglion- 

 cells of Carcinus are unipolar, and often the axis-cyl- 

 inder of the cell runs for a long distance before it 

 gives off the first dendrites and sends out the peri- 

 pheral fibre. It seemed very strange to me that a 

 stimulus entering through the sensory nerves into the 

 central organ should go through the dendrites to the 

 far-distant motor-ganglion cells, and travel the great 

 part of the same path before entering the peripheral 

 motor fibre, instead of going directly to the motor 

 fibre. It was easy to decide this question by sep- 

 arating the ganglion-cells with their axis-cylinder 

 process from the motor neurons without injuring the 

 neuropiles. If the ganglion-cell were absolutely es- 

 sential for the reflex, the muscles involved should 

 become paralysed immediately after the operation ; if 

 it were not essential, no paralysis should occur, at least 

 for some time, and the stimulus could go across 



