208 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
p. 231 (edition of 1895), a figure which Schafer has since incorpo¬ 
rated in his “ Essentials of Histology ” and in the tenth edition of 
Quain’s “ Anatomy.” J. M. Flint, ’99.1, has found an extensive con¬ 
nective tissue framework in the supra-renal, but it is very slight in 
its development, and does not affect the essential morphological 
relations, which this paper is intended to discuss. We shall recur to 
the question of the relation of sinusoids to connective tissue. The 
special character of the supra-renal circulation seems to have 
attracted only passing attention, and I think that the resemblance 
of the blood channels to the sinusoids of other organs is here 
pointed out for the first time. 
The observations of Hans Rabl, ’91.1, show, incidentally, that in 
the chick the type of the supra-renal circulation is the same as in 
mammals. I have confirmed this by observations on a chick 
embryo of eleven days (Harvard Coll. no. 255). 
6. Parathyroid gland. 
Schaper, ’95.2, p. 257, has 
explicitly emphasized the 
sinusoidal character of the 
parathyroid circulation in 
certain animals, and is the 
only author known to me 
who has emphasized the 
physiological importance of 
this type of blood vessels. 
He writes as follows concern¬ 
ing the sheep, — “ wo das 
Organ aus einem Netzwerk 
schmalerer oder breiterer 
Epithelbalken zusammenge- 
Eig. 12. From a section of parathyroid se t z t 1st, dessen Maschenrau- 
of the sheep. (From Prof. Schaper’s prep- 1 ~ 
A . 1 , A - . A me durch enorm weite Capil- 
aration, no. 444). Par., parenchyma; Si., . 1 
Si, sinusoids. ‘ laren vollstandig ausgefUllt 
werden.” He further points 
out that the endothelium 
is closely fitted against the parenchyma of the organ. By the 
kindness of Professor Schaper, I am able to offer Fig. 12, which 
is made from one of his original sections. Schaper’s drawings, 
l. c., Figs. 1, 2 and 3, represent the same features, together 
with accurate histological details. He terms these characteristic 
