406 The Arteriole Recta of the Mammalan Kidney 
ing his conclusions on observations made after injecting sodium sulphindigo- 
tate. It would seem, however, that absorption of the dye by the epithelium 
of the ascending limb of Henle’s loop and distal convoluted portions, after a 
concentration as a result of absorption of water in the descending limb is not 
excluded. Ribbert states distinctly that ‘‘a secretion of specific substances 
takes place only in the convoluted tubules of the first order, while in the 
loop of Henle, the distal convoluted portion and the collecting tubules, there 
takes place exclusively or for the greater part a resorption of water.” He 
further draws attention to the fact that in normal kidneys of older individ- 
uals there are often found pale yellow granules, contained exclusively in the 
epithelium of the distal convoluted portions and parts of the loops, and, 
further, that toxic agents secreted by the kidney affect first the glomeruli 
and then the distal convoluted portions and in part the loops. It would ap- 
pear, therefore, that a resorption takes place from these tubular segments 
perhaps of more specific substances than from the descending limb of Henle’s 
loop. 
(Excellent reviews of the literature bearing on renal secretion may be 
found in a number of recent publications—Ribbert, Untersuchungen tiber dis 
Normale und Pathologische Physiologie und Anatomie der Niere, Bibliotheka 
Medica, 1896; Hans Meyer, Herter Lectures, Bull. Johns Hopkins Hospital, 
Noy. and Dec., 1905; R. Metzner, Die Absonderung und Herausbeforderung des 
Harnes, Nagel’s Handbuch der Physiologie des Menschen, Bd. II, Erste Halfte, 
1906,—to which the interested reader is referred.) 
