DEVELOPMENT OF DIGITIFORM GLAND 



339 



the periphery of the gland as seen in transverse section (fig. 3). 

 They resemble closely the original outpouching of the gland 

 from the intestine. At the peripheral ends of the newly form- 

 ing tubules the epithelium is reduced to one or two layers of 



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ws. 



T -3- T.2. T.I. 



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Figs. 3, 4, 5, and 6 X 80. Transverse sections through the middle of the 

 digitiform gland of Acanthias embryos. 



Fig. 3 Embryo 28.1 mm. in length. 



Fig. 4 Embryo 33.1 mm. in length. 



Fig. 5 Embryo 47.5 mm. in length. 



Fig. 6 Embryo 95 mm. in length. 



Cent, lum., main central lumen; D.A., digitiform artery; Ep., epithelium; Int., 

 intestine; Mes., mesentery; T. 1, 2, 3, 4, 5, 6, tubules of the first to sixth orde ; 

 V.S., venous sinus; F.F.»S'., ventral venous sinus (digitiform vein). 



Only the larger vessels are shown. In figure 3 note the narrow lumen of the 

 intestine. 



