258 RICHARD E. SCAMMON 



necting stalk or plate, and, meeting, become confluent. It is 

 not until some time after these clefts have joined that the lumen 

 of the anastomosis acquires its full size and regularity. A late 

 stage in the establishment of this connecting channel is shown 

 in figure 27 from an embryo 19 mm, long (S.C. 3). Here the 

 clefts are still separated by a single cell. Figure 3 B is a graphic 

 reconstruction of the tubules involved in this anastomosis. 



Fig. 3 Graphic reconstructions of anastomosing hepatic tubules in Acanthias. 

 Detailed drawings of the sections indicated with dotted lines will be found in plate 

 2. A, tubules from an embryo 19 mm. long (S.C. 3) (see fig. 26). B, tubules from 

 an embryo 19 mm. long (S.C. 2) (see fig. 27). X 100. 



4. Later history of the hepatic cylinders 



a. Growth of the hepatic network. Immediately after anasto- 

 mosis has occurred the liver increases in size very rapidly. At 

 first this growth is due almost entirely to the increase in number 

 of the hepatic cylinders, but later the greater portion is brought 

 about by the tremendous enlargement of the hepatic sinusoids. 

 After anastomosis new cylinders are added to the existing net- 

 work in three ways : by the formation of tubules from the remains 

 of the hepatic pouches, by the formation of blind sprouts or 

 buds from the sides of cylinders forming the network and by the 

 production of new cylinders at the periphery of the network from 

 the cylinders located there. These methods of addition to the 

 hepatic network cease in the order given and the proportional 

 amount contributed to the network by the several methods is 

 in inverse order to that in which they are listed above. 



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