THE CARDIAC GANGLION. 



2O' 



They occupy the axial portion of the median cord, and are confined to the middle 

 and the posterior segments, none having been observed in the first three, or in the 

 last segment. 



The body of these cells is seldom fully impregnated with methylene blue. 

 The nucleus, central protoplasm, and spiral fibers may be faintly outlined, in 



FIG. 1 1 6. The lateral margin of the ganglionated median nerve of the heart of an adult Limulus, from the 

 region of the sixth cardiomere; it shows the two kinds of ganglion cells, C.n.c. and gn.c.; the clusters of neuropile, 

 n.p.; and the paccinian-like terminals, P.c., imbedded in the muscular substances of the heart. Methylene-blue 

 preparation. 



sharp contrast with the small, almost black, multipolar cells. Their enormous 

 axis cylinders, however, are usually deeply colored. They extend forward and 

 backward, apparently the whole length of the cord, bending from side to side, and 



