VEIN. 



1 377 



and semi-pellucid. It appears structureless to 

 the naked eve, and looks almost like a thin film 

 of fecula jelly (arrow-root made with water), or 

 rather, perhaps, like the flaccid dull cornea of 

 an animal dead some days. When separated, it 

 coils up, and, where the surfaces have become 

 adherent, it is difficult to unfold it again : it 

 novv looks and feels like thick mucus it is 

 semitrarisparent and adhesive. When seen 

 under the microscope, it is found to be indis- 

 tinctly fibrous ; some masses appear as a dense 

 web of flat fibres, the fibres being strictly on 

 the same plane, with their sides adherent at 

 some points, and leaving intervals at others ; 

 in some places the interspaces are only small 

 specks on the surface of what appears to 

 be in other respects, an almost homogeneous 

 sheet ; there are also some indistinct longi- 

 tudinal striations, connecting these minute 

 interspaces and obscurely indicating the out- 

 line of fibres. The element of which this 

 coat is composed is singularly pellucid under 

 the microscope, scarcely refracting excepting 

 at its edges. 



The fibrous mass of which the vein is com- 

 posed, in many places exhibits the appearance 

 as if the fibres were formed of spindle-shaped 

 cells strung together, with their ends over- 

 lapping; and these cells may be occasionally 

 isolated, they are spindle-shaped and have 

 an oval nucleus. They resemble those ob- 

 tained from the middle coat of the aorta of a 

 foetal pig, by Lehmann. (See his figure.) 



Whether this condition is the result of im- 

 perfect maturation of the tissue of which the 

 vein is composed, or otherwise, I am unable 

 to say. 



V. Valves. The valves are membranous 

 folds on the inner surface of the veins, having 

 a definite form and regular arrangement with 

 regard to their object the progress of the 

 venous blood to the heart, and obstruction to its 

 regurgitation. They are of peculiar interest 

 to the physiologist, as presenting a clear and 

 elegant specimen of animal mechanics; and to 

 the literary anatomist they are not less inter- 

 esting, as having been one of the main objects 

 which suggested to Harvey his brilliant de- 

 duction of the circulation of the blood. 



Crnveilhier states that the valves of veins 

 were first discovered by Etienne. Harvey 

 leaves the priority of discovery in doubt ; for 

 he writes, " The celebrated Hieronymus Fa- 

 bricius of Aquapendente, a most skilful ana- 

 tomist and venerable old man ; or, as the 

 learned Riolan will have it, Jacobus Sylvius, 

 first gave representations of valves in the 

 veins."* Fabricius himself lays claim to the 

 discovery, " non solum nulla prorsus mentio 

 de ipsis facta sit, sed neque aliquis prius base 

 viderit, quam anno Domini septuagesimo 

 quarto, supra millesimum et quingentesimum, 

 quo a me summa cum laetitia inter disse- 

 candum observata fuere."-)- Marx, who ap- 



* Harvey on the Motion of the Heart and Blood, 

 Sydenham Society's Translation, chap. xiii. 



f Fabricius, ab Aquapeudente. Opera oinnia Ana- 

 tomica, &c. Lips. 1687, p. 150. Fabricius calls the 

 valves by the felicitous term, "osteola," little doors. 



VOL. IV. 



pears to be profoundly versed in the literature 

 of this subject, says the discovery is due to 

 Erasistratus ; for he observes, " Erasistratus 

 (304 B.C.), item clarus anatomus jam snbtilius 

 in structural)! et usum venarum iuquisivit, 

 valvulas jam observavit."* 



Harvey's description of the valves is so 

 apposite and clear, as well as so interesting in 

 a literary point of view, that I shall quote it. 

 The valves, he observes, " consist of raised 

 or loose portions of the inner membrane of 

 these vessels, of extreme delicacy, and a sig- 

 moid or semilunar shape. They are situated 

 at different distances from one another, and 

 diversely in different individuals ; they are 

 connate at the sides of the veins ; they are 

 directed upwards or towards the trunks of the 

 veins; the two for there are, for the most 

 part, two together regard each other, mu- 

 tually touch, and are so ready to come into 

 contact by their edges, that if any thing at- 



Fig. 862. 



Venous Valves, after Fabricius.^ 

 a, femoral vein ; b, saphena interna. 



tempt to pass from the trunks into the branches 

 of the veins, or from the greater veins into 

 less, they completely prevent it; they are 

 further so arranged, that the horns of those 

 that succeed are opposite the middle of the 

 convexity of those that precede, and so on, 

 alternately." He further writes, " In many 

 places two valves are so placed and fitted, 

 that, when raised, they come exactly together 



* Marx. Diatribe Anatomico-physiologica de 

 Structura atque Vita Venarum. Carls. 1819, p. 6. 

 f Fabvicius, Opera oinnia, tab. iv. p. 157. 



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