320 THE DEVELOPMENT OF THE CHICK 
substance of the liver is derived. <A third diverticulum is dis- 
tinguished by Brouha as the right posterior diverticulum; this is 
an early outgrowth of the posterior diverticulum. Hepatic cylin- 
ders arise from both primary diverticula at an early stage, and 
these, branching and anastomosing, soon form a basket-work of 
liver tissue around the intermediate portion of the meatus venosus. 
The anterior diverticulum alone extends forward to the anterior 
Fia. 187. — Reconstruction of gizzard, duodenum, 
and hepato-pancreatie ducts of a chick embryo 
of 124 hours. (After Brouha.) 
D.ch., Ductus choledochus. D. ey., Ductus cys- 
ticus. D.h.ey., Ductus hepato-eysticus. D-h.d., 
Dorsal or hepato-enteric duct. Du., Duodenum. 
G. bl., Gall bladder. Giz., Gizzard. Pa. d., Dor- 
sal pancreas. Pa. v. d., Right ventral pancreas. 
Pa. v. s., Left ventral pancreas. 
end of the meatus, and it even encroaches on the sinus venosus, as 
we have already seen; in the posterior part of the meatus venosus, 
on the other hand, the liver tissue is derived entirely from the 
posterior diverticulum. The mesenchyme in the interstices of 
the hepatic framework is replaced almost immediately by blood- 
