CcBTis.—Planar ia. 
PLATE 14. 
(The figures are from camera lucida outlines of sections and are reduced 
three fourths in the reproduction.) 
Fig. 37. A sagittal section through the anterior end of a tail piece on the 
fourth day (figure 14). The essential structure of the adult head has 
been reached, there being now almost no formative cells anterior to 
the brain (n). The anterior is to the left, Zeiss D X 2. 
Fig. 38. From a sagittal section of a young tail piece (see figure 2). The 
part of the section drawn lies about in the middle of the animal and 
shows the excess of formative cells with frequent mitotic figures in 
the dorsal region. The anterior end is to the left. Zeiss D X 2. 
