350 JOHN BEARD, 



the other end, by means of a process of the external ganglion-cell, 

 extends over the tip of the myotome. This chain of applied ganglion- 

 cells is, as the sequel will prove, hardly to be looked upon as merely 

 a number of cells caught in the act of migrating outwards from the 

 spinal cord. Similar chains exist in much older stages, and of such 

 many only differ from the present one in the respect that in them 

 the bridge is not solely composed of ganglion-cells, but that there 

 are one or more axis- cylinders forming part of it. In Fig. 53 there 

 is another somewhat one-sided group of six centrally-lying cells, and, 

 in addition, a seventh one (sp. c) excentric in position, which is just 

 beginning to spin a process in the direction of the epiblast. 



In the next figure of the series (Fig. 52) a number of central 

 ganglion-cells are again encountered,, of these one has a process, which 

 can be followed to the myotome, running behind and closely applied 

 to two ganglion- cells {w.gl.c) placed bluntly end to end. Of these 

 two cells the one is in touch, by means of its nerve-process, with its 

 central fellows, the other possesses a process pointing in the opposite 

 direction over the myotome. 



Of another section no drawing is given, because it exactly re- 

 sembles Fig. 46 from a different series. 



Fig. 54 next calls for attention. In it one sees the long nerve- 

 process of a central cell — a process which differs from that in the 

 next figure in that near the myotome it becomes applied to a gan- 

 glion-cell {gl. c^). The last figure (Fig. 55) from the series is a 

 combination of the appearances met with in two consecutive sections. 

 It is intended to show among other things that the transient system 

 has in this embryo not yet reached the maximum of its development. 

 The summit of the cord is still in a state of unrest, as demonstrated 

 by the half-developed wandering ganglion-cell (w.gl.c) just beneath 

 the epiblast, and also by the cells projecting from the cord to the 

 right of the figure. On this side also there is a large wandering 

 ganglion-cell (w.gl.c) in close association with the cells of the spinal 

 ganglion. The figure was chosen out of many which revealed this 

 unrest chiefly on account of the short axis-cylinder process, with 

 embedded nucleus, which passes from among the ganglion-cells in 

 the cord upwards, until it touches the epiblast. The figure was made 

 into a combination so as to put in it the long naked axis-cylinder process 

 (n.p) of a central ganglion-cell which was present in the section 

 following that originally drawn. This process becomes lost to sight 

 among the cells forming the tip of the myotome. 



