68 



Cephalic visceral lymphatics 



The cephalic visceral lymphatics revealed in my injections 

 are found in the deep tissues of the branchial region, and are 

 drawn in figure 31 and text figure C (DP.PHGL.L., Int.Vscl. 

 L.). They were first recognized as lymphatics by their blue 

 color in double injections, in which Berlin blue in the lym- 

 phatics brought them out conspicuously against black ink in 

 the blood vessels. A deeper duct (the deep pharyngeal duct) 

 may be identified in the figures in the roof of the pharynx, 

 immediately overlying the dorsal aorta. It runs back to the 

 region of the anterior lymph heart, where it leaves the aorta, 

 and turns sharply dorsalward to connect with the 'anterior 

 collecting duct' of the lymph heart, well separated from the 

 junction of the abdominal duct with the heart vessels. These 

 cephalic ducts are drawn faintly in the plate figures as com- 

 pared with the adjacent lymph vessels. 



Just before it joins the * collecting duct,' the deep pharyn- 

 geal duct unites with another anterior lymphatic from the 

 more superficial tissues surrounding the ear vesicle (fig. 31, 

 Int.Vscl.L., and text fig. C). 



My paper of 1908 described the position and relations of 

 the anterior lymph heart as follows, 



"The lymph heart lies above the posterior portion of the pro- 

 nephros dorsally and outward from the myotomes nearer the 

 epidermis. It holds this position in embryos from 10 to 12 

 mm. The heart empties into the pronephric sinus (ductus 

 Cuvieri) just back of the last pronephric funnel and opposite 

 the glomerulus. It fills a corner bounded by the posterior 

 dorsal angle of the pronephros in front, the dorsal wall of the 

 coelom below, and the myotomes medially. The lateral nerve 

 gives off its dorsal branch just over the lymph heart." 



When the correction is made that the lymph heart empties 

 into the anterior vertebral vein (third intersegmental vein) 

 and not directly into the pronephric sinus, the general rela- 

 tions outlined in the early statement are readily verified in 

 the late larva illustrated in figures 30 and 31, though both the 

 lymph heart and the pronephros are partly hidden in the pic- 

 ture by the overlapping lymph plexus of the body wall. 



