164- THE MOTION OF THE BLOOD. 



bad example of some illustrious physiologists, but on the undis- 

 turbed vessels of recent subjects, v. c. on the innominata and its 

 two branches the right carotid and subclavian, on the brachial 

 and its two branches the radial and ulnar. f 



" The inconstancy of the proportion between the capacity of 

 the branches and that of the trunks is clearly shown by the various 

 sizes of the vessels under different circumstances, v. c. by the 

 relative capacity of the inferior thyreoid artery in the infant and 

 the adult ; of the epigastric artery in the virgin and the mother 

 near her delivery ; and also of the uterine vessels in the virgin 

 and the pregnant woman ; of the omental vessels during the 

 repletion and vacuity of the stomach. g 



" The arteries, after innumerable divisions and important 

 anastomoses 11 connecting different neighbouring branches, termi- 

 nate at length in the beginning of the veins. By this means the 

 blood is conveyed back again to the heart. The distinction 

 between artery and vein, at the point of union, is lost." 



Some arteries terminate in cells ; for instance, many of the 

 penis and spleen. 



** Another description of vessels arise universally from the 

 arteries, and are called colourless, from not containing pure blood, 

 either on account of their minuteness, or of their specific irrita- 

 bility, which causes them to reject that fluid." 



" The blood conveyed from the heart throughout the body by 

 the arteries is carried back by the veins.* 



11 These are very different in function and structure from the 

 arteries, excepting, however, the minutest of both systems, 

 which are indistinguishable. 



" The veins, except the pulmonary, are universally more 

 capacious than the arteries ; more ramified ; much more irregu- 



f " See also J. Theod. Van Der Kemp, De Vita. Edin. 1782. 8vo. p. 51. 



And Seerp Brouwer, Qutestiones Medic, varii argum. Lugd. Batav. 1816. 

 4to. p. 8." 



6 " This is remarkably observable in the adult stag, by comparing the areas of 

 the external carotid and its branches, during the spring, just before the horns 

 have attained their full growth, and when they are still covered with their downy 

 integuments (called in German, der Bast), with such as they are after this cover- 

 ing has fallen off." 



h " Ant. Scarpa, Sulf Aneurisma, Pav. 1804. fol. cap. 4." 



' " H. Marx, diatr. prtemio ornata t de structura atqiie vita venantw. Carlsr. 

 1819. 8vo." 



