242 DEVELOPMENT OF SUPRARENAL BODIES. 



end which, in succeeding sections, is entirely replaced by a sj^m- 

 pathetic ganglion. Wavy fibres (which I take to be nervous) are 

 distributed through the suprarenal body in a manner which, 

 roughly speaking, is proportional to the number of ganglion 

 cells. At the large end of the body, where there are few nerve 

 cells, the typical suprarenal structure is more or less retained. 

 Where the nerve fibres are more numerous at the small end 

 of the section, they give to the tissue a somewhat peculiar 

 appearance, though the individual suprarenal cells retain their 

 normal structure. In a section of this kind the ganglion and 

 nerves are clearly so intimately united with the suprarenal 

 body as not to be separable from it. 



The question naturally arises as to whether there are cells 

 of an intermediate character between the ganglion cells and 

 the cells of the suprarenal body. I have not clearly detected 

 any such, but my observations are of too limited a character to 

 settle the point in an adverse sense. 



The embryological part of my researches on these bodies 

 is in ireality an investigation of later development of the 

 sympathetic ganglia. The earliest stages in the development 

 of these have already been given \ and I take them up here 

 as they appear during stage L, and shall confine my descrip- 

 tion to the changes they undergo in the anterior part of the 

 trunk. They form during stage L irregular masses of cells with 

 very conspicuous branches connecting them with the spinal 

 nerves (PL xvii. fig. 3). There may be noticed at intervals 

 solid rods of cells passing from the bodies to the aorta, PL XVIL 

 fig. 2. These rods are the rudiments of the aortic branches to 

 which the suprarenal bodies are eventually attached. 



In a stage between M and N the trunks connecting these 

 bodies with the spinal nerves are much smaller and less easy to 

 see than during stage L. In some cases moreover the nerves 

 appear to attach themselves more definitely to a central and 

 inner part of the ganglia than to the whole of them. This is 

 shewn in PL xviii. fig. 8, and I regard it as the first trace of 

 a division of the primitive ganglia into a suprarenal part and a 

 ganglionic part. The branches from the aorta have now a 



1 Antea, pp. 438, 439. 



