Cervical Veins and Lymphatics in Human Embryos. 



35 



of the mandibular and hyoid arches, Avhich at its caudal end divides 

 into tv70 symmetrical parts. Each of these turns abruptly to one 

 side, receives small tributaries from the lateral parts of the branchial 

 arches, and empties, lateral to the aortic arches, into the anterior 

 cardinal vein. Later the vessel cannot be demonstrated. A part of it 

 may perhaps be incorporated in the external jugular vein." 



V.lmg-fi 



Fig. 1 Fig. 2 



Fig. 1. Reconstruction, as seen from the ventral side, of tlie riglit arm 

 and adjacent part of the body of a human embryo of 16 mm. ( Harvard Embryo- 

 logical Collection 1,000), to show the veins and lymphatic vessels. The latter, 

 in this and the three following figures, have been heavily shaded, x 20 diam. 

 Fig. 2. Similar reconstruction from a human embryo of 11.5 mm. (H. E. C. 

 189). X 20 diam. V. card, ant., Vena cardinalis anterior; V. card, com., V. 

 cardinalis communis (duct of Cuvier) ; V. card, post., "V. cardinalis posterior ; 

 V. Ung-fac, V. linguo-facialis ; V. scl. d., V. subclavia dorsalis ; V. scl. v., 

 V. subclavia ventralis ; V. th-ep., V. thoraco-epigastrica ; V. til. p., V. ulnaris 

 prima. 



This description is illustrated by an excellent reconstruction. Two 

 years later these veins were recorded in pig embryos of 6, 12, 14 and 

 20 mm.^ Because of their course across the throat they were called 

 "transverse veins." It was stated that the median vessel, instead of 

 bifurcating, sometimes passes wholly to the right and sometimes to 

 the left. The early appearance of corresponding veins in the rabbit 



*Lewis, F. T. The gross anatomy of a 12 mm. pig. Amer. Journ. of Anat, 

 1903, Vol. 2, p. 221. 



