Eben C. Hill 444 
in the cleared specimen. As in the human embryo, rotation of the kid- 
ney occurs before the entrance of the blood supply, as has been shown 
by Pohlman.’ My study of sections of pig embryos places the rotation 
of the kidneys in this genus between twelve and fifteen mm.” In the 
human embryo Pohlman has shown that the vascularization occurs be- 
tween twenty-five and thirty mm., while in the pig I find this vasculariza- 
tion of the kidney at twenty-eight mm. The adrenal, which is depicted 
EDTGeale IG 22 
Fic. 1. Cleared specimen of the testis, kidney, and Wolffian body of an 
embryo pig 33 mm. in length, showing the first appearance of vascular supply 
to the testis. x 6. W. B., right Wolffian body, 8.6 mm. in length; Ad., ad- 
renal; A.,-aorta; 7., testis measuring 2 mm. in length; S. A., spermatic ar- 
tery; K., kidney, 3.8 mm. in length; W. D., Wolffian and Miillerian ducts; 
U. A., umbilical artery. 
Fig. 2. Cleared specimen of the right testis, kidney, and Wolffian body of 
an embryo pig 48 mm. in length, showing the commencement of convolutions 
in the spermatic artery and the increased blood supply. xX 6. K., right 
kidney, 6.5 mm. in length; Ad., adrenal; W. B., Wolffian body, 10 mm. in 
length; A., dorsal aorta; R. A., renal artery; 7., testis, 3.5 mm. in length; 
S. A., spermatic artery; W. D., Wolffian and Miillerian ducts; U. A., umbilical 
artery. 
Medicine, Vol. VII, No. 25. 
Hill, E. C.: On the First Appearance of the Renal Artery and the Rela- 
tive Development of the Kidneys and Wolffian Bodies in Pig Embryos. Johns 
Hop. Hosp. bull., Vol. XVI. 
