TBE CAUDTAC OB GORONABT VEINS. 599 



nodulated appearance. Eemak found longitudinal muscular fibroa iu 

 the adventitta of the large veins of the Ox and Sheep, but chiefly in the 

 hepatic portion of the posterior vena cava and the veins of the liver.) 



Injection of the Veins. — To render the dissection and study of the veins more easy, 

 tliey ought to be filled with tallow or any other solldifiable matter, like the arteries. But 

 to attain this result the same mode of procedure cannot be employed as for them. 

 Instead of causing the injecting material to flow from the trunk into the branches, it is 

 necessary to propel it from the branches towards the trunk, because nf the presence of 

 the valves; this is to be done by successively fixing the canula into several venous 

 branches. 



Four injections generally suffice to fill the whole venous system in a satisfactory 

 manner. The first is made from the alveolar vein, beneath the masseter mutcle ; the 

 second from a digital vein of one or both anterior limbs, or from the side of the foot, 

 after having destroyed by a stylet the few valves which are sometimes found towards the 

 point of union in this vein ; or from the side of the heart. The third, from the posterior 

 digital veins, in the same way ; the fourth, by an intestinal vein. If any important veins 

 are empty after these four injections, a case of frequent occurence, they can be directly 

 injected. 



CHAPTEE 11. 



VEINS OF THE LESSER CIKOULATION, OR PULMONARY VEINS. 



The pulmonary veins comport themselves in the same manner as the 

 corresponding arteries. They are lodged in the substance of the lung (com- 

 mencing in the capillaries, upon the walls of the intercellular spaces and air- 

 cells, joining to form a single trunk for each lobe), and collect in from four 

 to eight trunks, which open into the roof of the left auricle, after emerging 

 from the pulmonary organ immediately above the origin of the bronchi. 

 As they are destitute of valves, they readily allow the blood to flow towards 

 their roots. It is tliey which carry to the left heart the fluid thrown into 

 the lung by the right ventricle, to be submitted to the revivifying influence 

 of the atmosphere. 



CHAPTER III. 



VEINS OF THE GENERAL OR SYSTEMIC CIRCULATION. 

 These vessels bring to the right auricle the blood which has been dispersed 

 in the texture of organs, by the ramifications of the great arterial tree. 



They open into the auricle by forming three groups: the group ot 

 coronary or cardiac veins; the anterior vena cava, and the posterior vena cava. 



Article I. — Cardiac or Cokonaey Veins. 



There are several small, and one large or great coronary vein. 



Small Cardiac Veins,— These are the almost insignificant vessels, un- 

 determined in number, which come from the walls of the right ventricle and 

 ODcn directly into the corresponding auricle at the coronary groove. 

 rAmone these may be included the debatable vense Thebesit, a multitude of 

 minute venules said to arise in the structure of the heart and open directly 



'''^^GeeItH^eoIaiiy Vein (Pigs. 258, 5 ; 259, o,jp).-This vein is formed 

 by two roots : one is lodged in the right ventricular groove, and accompanies 



