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W. F. E. WELDON. 
therefore, the blastema attached to the glomerulus gives rise 
only to suprarenal tissue. For this figure, I have purposely 
chosen a section in which the contact between the suprarenal 
rudiment and endothelium of the vena cava was as close and 
as extensive as possible, in order to show the distinctness 
which, in spite of their close apposition, exists between the two 
structures, and to contrast once more this distinctness of the 
vena cava endothelium with the irregular way in which the 
cells of the glomerulus wall are merged in the blastema. 
This section is also interesting from another point of view. 
One of the arguments used by Dr. Braun, in order to disprove 
the existence of any real connection between the rudiment of 
the testicular network and that of the suprarenal, is that the 
segmental rudiments of the former structures are well developed 
before the appearance of any suprarenal tissue at all. Dr. 
Braun believes that the whole of the outgrowth from each 
glomei’ulus becomes converted into a seminiferous tubule. 
But if this be so, what can be the function of such an outgrowth 
in front of the testicular region ? 
In fig. 5 is seen a section through the beginning of the 
generative ridge : the suprarenal and seminiferous rudiments 
are still continuous, but the one is a little more deeply stained, 
and its component cells are a little smaller than the other. As 
before, the endothelium of the surrounding blood-vessels forms 
a distinct layer over the blastema, the cells of which are quite 
sharply defined and clearly recognisable. 
The upward growth of the suprarenal rudiment, already 
well marked in fig. 5, is still better seen in fig. 6, from the 
middle of the trunk of an embryo of 13 mm. — almost the 
oldest in which a connection between suprarenal and semi- 
niferous tubules can be seen. In an embryo of 18 mm. 
(fig. 7), the separation has already taken place, and the 
suprarenal is cut off by blood-vessels from all adjacent struc- 
tures, though it remains now, as always before, perfectly 
distinct from the endothelium of the vessels themselves. 
This stage is only very slightly younger than the youngest 
figured by Braun, as fig. 4, PI. I. of his paper shows ; the 
