214 E. A. BAUMGARTNER 



The following table gives a list of the authors, the dates of 

 their publications and the material upon which their work on 

 the development of the liver and pancreas was based. 



Steinheim ('20) studied older embryos and observed the 

 attachment to the gut. Rusconi ('26) investigated younger 

 embryos and, as did Reichert ('40) and Vogt ('42), described 

 the ventral growth of the intestine to form the liver. Remak 

 ('55) and v. Bambecke ('68) differed from the above only in 

 the number of lobes formed and noted the close relation of 

 the gall-bladder to the right lobe. 



According to Goette ('75), the liver in Bombinator originates 

 as a ventral outpouching of the foregut posterior to the heart. 

 This diverticulum becomes separated from the gut by a gradual 

 cranio-caudal constriction, and the narrow connection which 

 remains forms the common hepatic duct. The outpouching 

 then grows by the production of folds or buds from its sides which 

 form the primary hepatic columns. The lumina remain in these 

 columns although they may be very small. Goette regarded 

 the early anastomoses and formation of the net-like hepatic 

 cylinders as aided by the ingrowth of a capillary network. The 

 gall-bladder develops as an outpouching of the posterior part 

 of the primitive hepatic duct caudal to which the ductus chole- 

 dochus is formed. 



Balfour ('81) made the statement that there is a single ven- 

 tral diverticulum from the gut which later develops into two 

 secondary branches and so forms the liver. 



Shore ('91) in his study on the frog found that the liver takes 

 origin as a ventral lengthening of the gut lumen into the mass 

 of yolk-cells which lies posterior to the heart. The yolk-cells 

 lining this lumen are transformed into hepatic cells and this 

 mass becomes partially separated from the gut. This constric- 

 tion is aided by the caudal growth of the sinus venosus. Later 

 there is formed at the expense of the yolk-cells and by cell-divi- 

 sion a large cell-mass into which the blood-vessels tunnel form- 

 ing a tubular gland whose columns divide and anastomose pro- 

 ducing a network interlacing with that of 'blood-lacunae.' 



