18 Development of Blood-Vessels of Human Brain 



Island the extravasation is extensive, while over the rest of the brain it is 

 in spots along the arterioles, as they penetrate the brain. 



Fig. 3. Embryo of the fourth week (No. 2). Enlarged 16 times. The 

 external form is from nature. The structures within the head have been 

 reconstructed; the tenth and twelfth cranial nerves and the first cervical 

 nerve by Dr. Streeter. 



Fig. 4. Brain and its arteries of embryo No. 163. Enlarged 15 times. The 

 picture of the brain is from a wax-plate model by Dr. Lrewis. The arteries 

 are from a graphic reconstruction. The basilar artery extends throughout 

 the length of the hind-brain and the circle of "Willis throughout that of the 

 fore-brain. The position of the cranial nerves and otic vesicle is given in 

 Fig. 9. 



Plate II. 



Fig. 5. Graphic reconstruction of the head of embryo No. 75, showing the 

 arteries and the brain. Enlarged 7 times. 



Fig. 6. Graphic reconstruction of the brain and arteries of embryo No. 

 145. Enlarged 7 times. 



Fig. 7. Same as Fig. 6. The right cerebral hemisphere has been removed, 

 showing the anterior cerebral artery throughout its extent. 



Fig. 8. Same as Fig. 7 with the choroid plexus and large veins added. 



Fig. 9. Embryo No. 163. Enlarged 13 times. The surface view is from 

 an excellent photograph, and the structures in the head are from a graphic 

 reconstruction. 



PLxVTE III. 



Fig. 10. Graphic reconstruction of the veins and brain of embryo No. 74. 

 Enlarged about 10 times. 



Fig. 11. Graphic reconstruction of veins of the head and brain of embryo 

 No. 144. Enlarged about 7 times. 



Fig. 12. Section through the head of embryo No. 109. Enlarged 12^4 

 times. H, hypophysis; S. Ob, superior oblique muscle; Ex. R, lateral oblique 

 muscle; Tr, trapezius; YJ, jugular vein. The cranial nerves are numbered 

 with Roman numerals. On the side lettered the section is nearer the mouth 

 than on the other side, showing that the vena capatis lateralis which con- 

 nects with the jugular vein is on the outside of the skull. 



Fig. 13. Head of embryo No. 109. Enlarged 12il> times. The form of the 

 arm and body are from photographs. The face, brain and nerves are from a 

 wax-plate reconstruction by Dr. Lewis. The veins are from a graphic recon- 

 struction. The brain and face are somewhat distorted, but are given in this 

 way to complete Fig. 5, Plate IV, in the publication of Bardeen and Lewis in 

 vol. I of this journal. 



