ON THE SUPRARENAL BODIES OF VERTEBRATA. 147 
distance from any vessel, and the later tissue only approaching 
one when it has so greatly increased in size as to have pushed 
all the intervening mesoblast, so to speak, on one side. There 
is no possibility of believing, in this case at least, that the 
walls of the blood-vessels have the slightest share in the pro- 
duction of the cortical blastema. 
The great difference between the results of the investigations 
of previous observers and those which have just been described, 
is sufficiently obvious. If, however, the accuracy of my 
observations be admitted, we have a much more rational expla- 
nation of the phylogeny of the suprarenals than is possible if 
we adopt the view of Braun, and others ; — an explanation which 
receives support, both from the anatomical relations of the 
adult organs, and with those of the corresponding organs in 
Myxinoids and Teleosteans. 
In Bdellostoma, I have already 1 attempted to show that 
the head kidney has become modified so as to form an organ 
functionally analogous to the suprarenals ; while in Teleos- 
teans, a most remarkable series of modifications, affecting 
every region of the kidney, has been described by Balfour and 
Emery ; a series which seems to me to supply every stage 
needful to complete our conception of the passage from such a 
form as Bdellostoma to that of a higher vertebrate. Balfour 
showed 2 that the head kidney of many adult Teleosteans con- 
sisted, not of renal tissue, but of a mass of parenchymatous 
“ lymphatic ” material, richly supplied with vessels, whose 
function, whatever it might be, was certainly not that of a 
normal kidney. He afterwards found the same kind of modi- 
fication to exist in the head kidney of the Teleosteoid 
Ganoids . 3 
Though the observations of Balfour left it highly probable 
that the “ lymphatic ” tissue described by him was really a 
result of the transformation of part of the embryonic kidney, 
1 This Journal, April, 1884. 
! This Journal, 1882. 
J “On the Structure and Development of Lepidosteus,” ‘Phil. Trans.,’ 
1882. 
