THE AXTKIHOB VENA CAVA. 613 



"The general disposition of the venous canals in the texture of the 

 reticnlmn supporting them, closely resembles that of the secondary ribs of 

 tin- limb (or lawlimr titi'rithal) of certain asymmetrical leaves. In their 

 course they follow un irregularly-broken line, intercepting each other by 

 joining at short intervals, so as to form unequal-sized, unsymmetric, 

 p< ly.u'i'iKil spaces. 



' These venous conduits have a double canal for discharging themselves : 



I ml, the least considerable and least constant; the other peripheral 

 ni,ij!>.r. corresponding to the artery of tho same name,' and whose 



satellite vein it is. 



" Central canal. Tho central canal is formed by tho simultaneous 

 anastomoses of a crowd of venous ramifications converging towards the 

 centre of the digit. It is of a parabolic shape, and embraces in the concavity 

 of its curvature the point of the pyramidal body, whence it throws its two 

 branches in a parallel manner on the sides of that body, into the bottom of 

 the lateral lacunas as far as tho cartilaginous bulbs, where it proceeds 

 to the external coronary plexus. This disposition is not constant, however, 

 as specimens are frequently met with in which this central canal is replaced 

 by multiple veins, which are more considerable than those forming the 

 whole of the plexus, and which serve them as overfalls towards the super.- 

 ficial coronary plexus. 



Circumflex vein, or peripheral venous canal. '* This vein is of large 

 calibre, and formed by divergent ramifications from the solar plexus, as will 

 as the descending veins of the podophyllous plexus ; it margins the external 

 limb of the villous tissue in following a slightly undulous line within the 

 circumflex artery, whose satellite it is. It is sometimes broken up, at 

 certain points of its course, into several smaller canals which are continuous 

 with its trunks. 



" In its circular route, all the divergent solar and descending podo- 

 phyllous veins are discharged into it, and it terminates, at the extremities of 

 the crescent formed by the third phalanx, in several largo branches which 

 pass beneath the podophyllous tissue to tho lateral cartilage, where they 

 concur to fo.^i the superficial coronary plexus. 



" B. PODOPHYLLOUS VENOUS PLEXUS OK NETWORK. The veins of tho 

 podophyllous plexus exhibit a disposition analogous to those of the solar 

 plexus ; like them, they are sustained in tho meshes of a fibrous texture (tho 

 !um processifjeriim of Bracy Clark, the svbpodoplitjUanx ><//(// of 

 French Vi-t linarians) spread on tho anterior surface of the bone, in tho 

 same way as the prriost um is on other bones, and continuous with tho 

 corium of the laiinnal tissue. Communicating largely between each other 

 by multiple anastomoses, like the solar plexus, they appear to be completely 

 i>.,lat'<l from the deeper parts, from which it is commonly believed they 

 emanate. 



" Tortuous and split up into branches in their course, tho podopEyllous 



- wind in a serpentine manner along the length of the lamina; they e>v. r, 

 very close to each other, and forming narrow elongated nn slu-s. Their 

 cmilltienco is such, that at certain points they appear bound together by their 

 external walls. 



" The calibre of these vessels is tolerably uniform throughout tho extent 

 of the podophyllotlfl plexus, except towards tho posterior parts, where their 

 principal canals empty themselves into the coronary plexus. 



"The podophyllous veins are in anastomotie communication, below, with 

 1 The inferior circumflex artery of the /not. 



