26 
indicative of a lack of distinct cellular structure; whether this differ- 
entiation was an artifact, and more apparent than real, due to the con- 
dition of the material, may better be left for decision when fresh 
material can be examined. The dorsal, ventral, and proximal margins 
of each half of the band present a condensed appearance which in 
not a few sections is indicative of a distinct membrane. 
Toward the lateral line, corresponding to a frontal plane of the 
worm, the dorsal and ventral halves of the lateral bands are distinctly 
separated. This separation is due primarily to the single, middle row 
of cells mentioned above. The nuclei of these cells can be very dis- 
tinctly seen both on surface views and on section, but it is more diffi- 
cult to trace the centripetal portion of the cells themselves. In some 
sections the cells could be quite distinctly followed to the proximal 
borders of the two halves of the band, nameh^ to the point at which the 
gland (to be described below) meets the marginal point between the 
two halves of the band. The picture obtained was strongly indicative 
of an interpretation that the middle row of cells in question acted as a 
connective element between the gland and the subcuticula. Such an 
intrepretation was not confirmed, however, by some of the sections, for 
the cell could not be traced to the proximal margin, and the space not 
occupied by the cell appeared not unlike a canal; the possibility is by 
100 ^ 
Fig. 17. 
