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in f^ig. 5 h, the cells of the ciliated and cover layers are in- 

 terrupted at about the point marked b.r. (Pip. o h) and at the 

 same time the side pouch (p.) of the groove (v.c.p.) becomes 

 separated from the groove itself along the line x-y (Fig. 5 h). 

 By the union, now, of the medial end (1) of the ciliated layer 

 with the end (l') of the adjacent side of the proove, and at the 

 same time by the union of ends 2 with 5* ' and 3 with 3 ' , we have 

 a condition represented in Fig. 5 i. The end (4) of the cover 

 layer unites with itr> fellow of the opposite side of the gland 

 to form the swollen upper edge of the partition (m.l., Fip. 5 i) 

 mentioned above. Py a careful comparison of Figs. 5 h and 5 1, 

 the relationships just described v/ill become clear. 



In Fig. 5 i, then, v/e have represented a section pas- 

 sing directly through the duct of the gland, o,nd we see that the 

 secretion from the two groups of gland cells (g.r.) passes out 

 of the gland in tv/o v;ays; that from the ventro-median group 

 passes into the central ciliated chamber (m.c.h.) and thence 

 directly out through the duct (v.c.g.), while the secretion from 

 the dorso-lateral group has to pass into the duct through the 

 side pouch (p.). Anterior to the duct, the ciliated chambers 

 (m.c.h. and l.c.h.) being one, (Fig. 5 f, m.c.h.), the secretion 

 from the different groups of cells may of course pass out either 

 way. The duct is inclined somewhat in a posterio-vontral direc- 

 tion and is lined v/lth ciliated columnar cells. The point at 

 the end of the line 1 (Fig. 5 i) Indicates the place of union of 



