486 



THE ABSORBENTS. 



of the pericardium, the vestigial fold of the pericardium, so named by Marshall, to 

 whom is due the first full elucidation of the nature and relations of the left primitive 

 vena cava. 



The left duct of Cuvier has been observed persistent as a small vessel in the adult. 

 More frequently a right and left innominate vein open separately into the right 

 auricle, an arrangement which is also met with in birds and in certain mammalia, 

 and which results from the vessels of the left side being developed similarly to those 

 of the right, while the cross branch remains small or absent. (Quain on the Arteries, 

 plate 58, figs. 9 and 10.) 



Fi<*. 331. Fig. 331. VIEW OF THE FOSTAL HEART 



AND GREAT VESSELS, FROM THE LEFT 

 SIDE, TO SHOW THE VESTIGE OF THE 

 LEFT SUPERIOR CAVA VEIN IN SITU. 

 (This figure is planned after one of 

 Marshall's, and slightly altered accord- 

 ing to an original dissection.) 



a, right auricle; &, left auricle and 

 pulmonary veins ; e, the conus arteriosus 

 of the right ventricle; d, the left ven- 

 tricle ; e, descending aorta ; + , vestigial 

 fold of the pericardium ; /, arch of the 

 aorta, with a part of the pericardium 

 remaining superiorly ; g, main pulmonary 

 artery and ductus arteriosus ; g', left pul- 

 monary artery ; 1, 1', right and left in- 

 ternal jugular veins ; 2, 2', subclavian 

 veins ; 3, right innominate and superior 

 vena cava ; 4, left innominate cr com- 

 municating vein ; 5, 5', remains of the 



left superior cava and duct of Cuvier, passing at + in the vestigial fold of the pericardium, 

 joining the coronary sinus, 6, below, and receiving above the superior intercostal vein, 7 ; 

 7', 7', the upper and lower intercostal vein, joining into one. 



A case is recorded by Gruber, in which the left vena azygos opened into the 

 coronary sinus, and was met by a small vein descending from the union of the sub- 

 clavian and jugular. (Reichert and Dubois Reymond's Archiv, 1864, p. 729.) In 

 this case, the jugular veins had been developed in the usual manner, while the left 

 vena azygos continued to pour its blood into the duct of Cuvier. 



(Consult Kolliker, Entwickelungsgeschichte, p. 414, et seq. ; J. Marshall on the 

 Development of the great Anterior Veins in Man and Mammalia, in Phil. Trans., 

 part i., 1850; and Wenzel Gruber, Uber die Sinus Communis und die Valvulse der 

 Venae Cardiacae, &c., in Me"m. de TAcad. imper. des Scien. de St. Petersbourg, 1864 ; 

 and in Virchow's Archiv, Jan. 1865.) 



THE ABSORBENTS. 



The absorbent vessels are divisible physiologically into two sets ; the 

 lacteals, which convey the chyle from the alimentary canal to the thoracic 

 duct ; and the lymphatics, which take up the lymph from all the other parts 

 of the body, and return it into the venous system. Anatomically con- 

 sidered, however, the lacteals are not different from the lymphatics, and 

 may be regarded as the absorbents of the mucous membrane of the intestine. 

 The larger lacteals and lymphatics are provided with valves, which give them, 

 when distended, a somewhat moniliform appearance j and both are connected 

 in their course with lacteal or lymphatic glands. 



