CuKTis.— Planavia. 
PLATE 15. 
(The figures are from camera lucida outlines of sections and are reducc'd 
two thirds in the reproduction.) 
Fig. 39. From a sagittal section of a tail piece on the 3d day. The pait 
shown is in the region of the newly formed anterior gut ramus and 
the rudiment of the pharynx (see figure 5). Only the anterior half 
of the mass of cells (p/P) destined to form the pharynx is shown. 
The anterior end is to the right. Zeiss D X 2. 
Fig. 40. A similar section through the region of the newly formed pharynx. 
The sheath {ps) is formed, hut the mouth has not broken through 
(see figure 19). The lumen of the pharynx (phV) is just appearing. 
The anterior is to the left. Zeiss D X 2. 
Fig. 41. A sagittal section through the anterior tip of the new median gut 
ramus of a tail piece (see figure 5) to show the close association of 
the formative cells (.s) with the gut (g) at this point. The anterior is 
to the right. Zeiss X 2. 
Fig. 42. A sagittal section through the tip of new tissue on a tail piece (fig¬ 
ure 4) of the 3d day. The new ectoderm is formed and in place of 
the large formative cells of the first day (figure 35) are found many 
smaller nuclei wdth no distinct cytoplasmic outline. The anterior is 
to the right. Zeiss T) x 2. 
