56 THE HISTORY OF ANIMALS. [B. IIL 



3. Both the aorta and the great vein continue as far as 

 the kidney each as a single duct ; from this point they are 

 more closely united to the spinal column, and are each di- 

 vided into two parts, like the letter lambda (A), and the 

 great vein is placed farther back than the aorta. The 

 aorta is more closely united to the spinal column, near the 

 neart, and the junction is formed by small sinewy veins. 



4. The aorta leaves the heart as a large hollow passage, 

 but as it advances it becomes narrower and more sinewy. 

 Prom the aorta, veins extend also to the mesenterium, like 

 those from the great vein, but far inferior in size, for they are 

 narrow and muscular. They terminate in small hollow 

 muscular veins. No branch of the aorta extends to the 

 liver and the spleen, but the branches of either vein extend 

 to each hip, and both touch upon the bone. Branches 

 reach the kidney both from the great vein and the aorta ; 

 they do not, however, enter the cavity, but are taken up in 

 the* substance of the kidney. 



5. Two other strong and continuous passages reach from 

 the aorta to the bladder, and others from the cavity of 

 the kidney ; but these do not communicate with the 

 great vein. From the centre of each kidney a hollow 

 sinewy vein passes through the other veins to the spinal 

 column; first of all they disappear upon each hip, and 

 then appear again in branches towards the hip ; their ex- 

 tremities are distributed upon the bladder and penis in 

 the male, and upon the uterus in the female ; no branch 

 of the great vein passes to the uterus, but many and thick 

 ones reach it from the aorta. 



6. Prom the aorta and great vein branches are distributed 

 to the nates ; at first they are large and hollow, afterwards 

 they pass through the legs, ending upon the feet and toes ; 

 and others again pass through the nates and thighs, alter- 

 nately from right to left, and they join with other veins 

 below the knees. 



7. The nature and origin of the veins are evident from this 

 description. In all sanguineous animals, the nature and origin 

 of the principal veins are the same, but the multitude of smaller 

 veins is not alike in all, for neither are the parts of the same 

 nature, nor do all possess the same parts. Nor are the veins 

 equally apparent in all animals ; but they are more manifest in 



