400 The Arteriole Recte of the Mammalian Kidney 
ous tubules, which tubules have later disappeared, a portion of the glom- 
erular plexus with afferent and efferent vessels remaining intact as a 
rete mirabile, the degree of retrogressive change varying with different 
glomeruli and in some instances going on to a complete obliteration of 
the glomerular plexus, the afferent and efferent vessels alone remaining 
as a continuous structure. As has been expressed to me—* The mill- 
dam remaining after the mill has disappeared and in some few instances 
the dam itself disappearing.” According to this hypothesis (for the sub- 
Fic. 2. Corrosion preparation of terminal arterial branches from kidney 
of dog. 
stantiation of which it is difficult to obtain definite data, as my attempts 
to obtain corrosion preparations of the arterial system of foetal kidneys 
and of kidneys of new-born dogs have not been successful), the arterial 
twigs which end in arteriole recte without the interposition of glomeruli 
—arteriole rectee vere—and the arterial twigs in the course of which are 
found retia mirabilia prior to ending in arteriole rectw are to be regarded 
as derived from glomeruli with afferent and efferent vessels, the glom- 
erulus in each instance degenerating in whole or in part consequent to 
the disappearance of the uriniferous tubule with which said glomerulus 
