138 
W. F. R. WELDON. 
important papers by Braun 1 and Mitsukuri, 2 the one dealing 
with the development of the suprarenals in lizards, the other 
in mammals. 
In lizards, Braun describes the cortical substance as arising 
“ as a thickening in the walls of the vena cava inferior.” In 
the earliest stage figured by him, a large mass of cortical 
blastema is already established, as seen in PI. 1, fig. 4 of his 
paper. In this figure, as in all the others given by Dr. 
Braun, it is noticeable, as he himself says, that “ the flattened, 
nucleated endothelium (of the blood-vessel) is easily to be 
distinguished ” from the adjacent tissue, and that it shows no 
sign of proliferation. It is therefore difficult to conclude from 
this account that the suprarenals arise as appendages of the 
blood-vessels themselves, Braun’s observations throwing little 
more light upon the real origin of the cortical substance than 
did the earlier ones of Balfour. 
In the same way Mitsukuri, treating of mammals, finds the 
first rudiment of the cortical substance in a little knot of 
isolated mesoblast cells “ on each side of and ventral to the 
aorta, on the inner side of the Wolffian bodies, and dorsal to 
the mesentery.” 
Gottschau, in a later paper 3 has described in mammals 
phenomena nearly in accordance with those observed in lizards 
by Braun, — emphasising more than Mitsukuri the connection 
between the cortical substance and the adjacent blood-vessels. 
From none of these observations can we learn anything of 
the mode of origin of the blastema described, each author 
taking up its history at a point when the cells composing it 
have already lost any connection which they may primitively 
have possessed with another embryonic organ. Janosik 4 has 
attempted to trace the earlier history in mammals, and has 
1 “ Bau u. Entwick. d. Nebennieren bei Reptilien,” Semper’s * Arbeiten,’ 
Bd. v. 
2 “ On the Development of the Suprarenal Bodies in Mammalia,” ‘ Quart. 
Journ. Mic. Sci.,’ 1882. 
3 ‘ Archiv. fur Anat. u. Phys.,’ 1883. 
4 ‘Archiv fiirMikr. Anat.,’ 1883. 
