2i6 TWENTY-FIRST LECTURE. 



manifold turnings, through the narrow spaces between the 

 ganglion bodies, to subsequently reassociate themselves with 

 the out- coming (single or multiple) nerve trunks. 



This arrangement does in reality (combined, it is true, 

 with transitions) occur. We already know that the ganglion 

 cell enters into communication with the nerve fibre (Fig. 1 75)- 

 In the ganglia of fishes and amphibia, the connective tissue 

 is weakly developed ; the elements are, therefore, more 

 readily isolated, still we have by no means any satisfactory 

 results to report. The ganglia of higher animals are, how- 

 ever, permeated by an exuberant fulness of firm connective 

 tissue ; picking them apart yields us, unfortunately, only the 

 fragments of the nervous contents. 



The requirements of the physiologist, who desires an in- 

 sight, cannot at present suffice here for the microscopist, and, 

 indeed, should not. For he would have to combine an im- 

 perfect perception with hypotheses into an abstract image. 

 For the coming races of men, the light of a better intelli- 

 gence will be kindled at some future day. We grope about 

 in the dark. 



Let us take a spinal ganglion of the fish, with its ganglion 

 bodies. The greater portion of the latter are certainly bi- 

 polar, that is, the cell is interpolated into the course of a 

 broad sensory fibre of the spinal cord (Fig. 175, a). 



Since the elements of the sympathetic in fishes exhibit 

 narrow medullated nerve fibres, we should accordingly de- 

 clare the nerve fibres connected with ganglion bodies to be 

 sensory elements of this division of the nervous system {U). 



One meets in our ganglia, furthermore, with smaller uni- 

 polar cells (c). Their narrow, sympathetic nerve fibre passes 

 downwards and spreads out peripherically. The ganglion 

 might, with these latter constituents, be one of the many 

 centres of the sympathetic, like all the remaining ganglia of 

 the fish's body. 



Even in the frog, however, the matter becomes much more 

 difficult. The presence of bipolar ganglion cells, interpo- 

 lated into the course of a sensory fibre of the spinal cord, 



