I'- net /.'. Sdbin. 



the time, and he has published, with my permission, a valuable recon- 

 struction <>f in;. ten in the Anatomical Record for L912 (Kamp- 

 meier 66 ). 



I • thoracic duel needs to be considered in relation to the reins 

 region. I g. 11 is a section through the seventh cervical verte- 

 bra of an embryo pig 19 mm. long, which i> before the thoracic duct 

 i complete vascular injection. Ii n ill be seen that 

 there is a vascular zone ventral to the vertebra, and from this zone 

 veins surround the sympathetic nerves and enter the dorso-medial 

 border of the internal jugular vein. The esophagus has a plexus of 

 blood vessels in the submucosa, but dorsal to the esophagus is a non- 

 vascular zone of loose connective tissue. The jugular stem of the 

 thoracic duct grows into this non-vascular area dorsal to the esopha- 

 - i- Bhown in fig. 12 from 23a. In this tracing; of the section 

 the veins are arbitrarily made black and the lymphatics are shown 

 empty, though in the section the left lymphatic sac and its ducts w< 

 injected. The thoracic duct lies in the margin of the vascular zone. 

 \- Kampmeier's reconstruction of this specimen show-, there is a 

 considerable plexus of lymphatics dorsal to the esophagus nea; their 



place of origin from the jugular sac. This plexus c sets with the 



left jugular sac in three places. From the injected plexus a short 



duct follow- the left cardinal vein and I think grows to the heart 



and lungs. A longer vessel crosses to the right side and i- the jugular 

 men! of the thoracic duct. This crossing of the duct behind the 

 aorta I have frequently, though not always, noted in older stages. 



The right lymphatic duct curve- ventralward and -row- t • > the heart 

 and lungs. 1 1- course is shown in Ii;:. 13 for an embryo 25 mm. long. 

 The asymmetry of the thoracic duct is confined to the jugular portion 

 and corresponds with the asymmetry of the aorta. It is interesting 

 to note that Sala I 137, Taf. 1 I. Fig. 16) and Pensa I 104, Taf. 15, 

 Fig. Vi picture a symmetrica] thoracic duct m the bird. 



The position of the cisterna chyli has already been shown in figures 

 9 and in. The cisterna chyli and lower part of tlie thoracic duct 

 arise in common with the iliac sacs from the mesonephritic veins on 

 either side, a- -hown in fig. '.'. These lymphatic buds from the two 

 ■ dorsal to the aorta and grow both cerebralward and. caudal- 

 ward along the dorsal wall of the aorta. This makes an abundant 

 plexus of blood-filled lymphatics along the ionise of the abdominal 

 aorta. Anj sections of pig embryos of this stage will show that the 



