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ARTHUR E. GILES. 
The way in which this conversion of kidney parenchyma into 
fat takes place is a true fatty degeneration, and not simply a 
fatty infiltration, though the latter occurs in the first stage. 
The change is seen best in the cells lining the glomeruli 
and renal tubules.' The clearly defined margins of the cells 
become hazy, and the nuclei less distinct ; fatty droplets 
appear at various parts of the cell and run together. The 
cells do not, however, swell up as the fatty matter invades 
them, but their protoplasm becomes replaced by it. At a later 
stage the contents of the cell consist only of fatty granules and 
granular detritus. 
For a while the outlines of the convoluted tubules can still 
be made out, as in fig. 6, the line of distinction between normal 
and degenerated kidney being well marked. But soon all trace 
of structure disappears, and there remains only a uniformly 
granular-looking mass, as in fig. 2. This is the fat-body, 
or corpus adiposum. 
We have thus answered the first question that we proposed, 
“ How come the fat-bodies to be in relation with the anterior 
end of the kidneys ? ” There further remains to be considered 
tbe question, “ How does the transition from this condition to 
that found in the adult take place ? ” 
When the hind limbs of tbe tadpole have appeared they 
develop fairly rapidly, the fore limbs sprouting out somewhat 
later. The condition of the “ tailed Frog ” is now attained. 
While this is going on a change takes place in the urino-genital 
organs, which, as regards the time at which it occurs, varies 
somewhat in different tadpoles, but usually begins during the 
period in which the tail is commencing to atrophy, and is for 
the most part completed by the time the tail is quite absorbed. 
This change is as follows : the anterior end of the nephros 
grows ventrally, and becomes secondarily attached to the 
anterior end of the genital organ, ovary or testis, as the case 
may be. Fig. 7 shows the urino-genital organs during this 
intermediate stage of transition, the fat-body (/.) being directly 
continuous both with the kidney ( k .) and with the genital 
organ ( g .). 
