MINOT: VEINS OF THE WOLFFIAN BODIES IN THE FIG. 271 
epithelial surface of the renal tubules, the curves of which the 
endothelium follows closely. In a true capillary the endothelium 
on the contrary follows, so to speak, its own and independent curve. 
The figure in the text illustrates the facts recorded. [Since this 
article went to press, I have examined the kidney of Necturus 
maculatus , for which material I am indebted to the kindness of 
Dr. G. H. Parker. In this representative of the Urodela, I find 
the same circulatory conditions as in Rana, but with wider sinuses.] 
The peculiar type of circulation to which I have called attention 
has, I believe, greater morphological (and physiological) importance 
than has been recognized. Comparison with the rete mirabili of 
various animals, for instance with the carotid gland of the frog, at 
once suggests itself. Even nearer lies the comparison with the form 
of circulation in two embryonic organs — the liver and the pronephros. 
As regards the liver, the comparison is especially facile in those lower 
types, in which the hepatic cylinders are tubular in form — compare 
the figure and brief description, which I have given in my “ Human 
Embryology,” p. 761, of the liver of an Acanthias embryo. As 
regards the pronephros, I will record that in tailed Amphibia, tele- 
osts, and ganoids, I have observed the same circulatory conditions. 
As specific evidence on this point I will put down the references to 
certain sections in our collection. 
These are: — 
Necturus, 15.0 mm. Transverse Series 78, Sections 300-330 
a 
a tt 
Frontal 
it 
80, 
{( 
95- 97 
tt 
18.0 “ 
Transverse 
tt 
16, 
it 
335-345 
it 
it (6 
Frontal 
it 
84, 
it 
95-100 
Ameiurus 
9.0 “ 
Transverse 
tt 
85, 
ii 
55- GO 
it 
it it 
Frontal 
tt 
87, 
a 
45- 50 
Batrachus 
9.5 “ 
Transverse 
tt 
118, 
a 
218-236 
ti 
ti it 
Frontal 
it 
120, 
a 
100-104 
Amia, 
10.0 “ 
Transverse 
a 
19, 
a 
260-270 
ii 
it it 
Frontal 
ft 
20, 
a 
60- 67 
ti 
13.0 “ 
Transverse 
it 
55, 
a 
231-240 
ti 
it ti 
Frontal 
tt 
57, 
a 
74- 78 
In the two teleostean forms, Ameiurus and Batrachus, and in the 
ganoid, Amia, the greater part of the space between the pronephric 
tubules is occupied by the blood channels, but there are also patches 
of tissue, the “ Pseudolymphoidgeioebe ” of W. Felix, 97 . 1 , p. 443. 
In these patches the nuclei are crowded together, and they differ by 
