36 MORGAN. [Vou xe 
ciliated area along its anterior wall. The anterior body-cavity 
(J.c.1) is larger and its dorsal wall thickened. On each side 
of the stomach the horns of this body-cavity are cut. They 
have left the stomach wall at this level and pass out towards 
the sides of the ectodermal wall. In sections they cannot 
always be traced into connection with the wall, but surface 
views seem to show that they do unite with the wall. The 
entrance to the tube leading to the mouth is shown in the 
lower portion of this figure. Three cross-sections of the tube 
and of the oesophagus, cut at a higher level, are shown in 
Figs. 27 and 28 aand 6. The first of these (Fig. 27) cuts the 
tube leading to the mouth at a level anterior to Fig. 26, and 
shows more in detail the structure of the tube. Four ciliated 
areas are cut, corresponding to the two limbs of the bands 
passing above and below the mouth at the top of the tube. 
In Fig. 28 a@ the section cuts the first part of the oesophagus. 
Two broad ciliated areas are found on opposite sides of the 
oesophagus, and these at the mouth are continuous with the 
ciliated cells of the band above and below. In Fig. 280 
the oesophagus is cut near its union with the stomach. Its 
walls are thicker and the lumen ciliated. Avound the outer 
surface are numerous muscle cells. 
The second and third body-cavities are shown best in longi- 
tudinal sections of the larva. Fig. 29 (Zezss 2, AA) is a por- 
tion of a longitudinal section of the larva along the side wall 
(right or left). Attached to the inner surface of the circular 
band is an irregular mass of cells forming the third body-cavity 
of that side (d.c.3). Above this and attached to the ectodermal 
wall, above the horizontal limb of the longitudinal ciliated band, 
is another mass of cells—the second paired cavity of that 
side (d.c.2). These body-cavities are shown more in detail in 
Figs. 30 and 31. Fig. 30 shows that the third pair is closely 
attached to the inner surface of the ectoderm. The nuclei of 
the mass are arranged to some extent into two distinct walls, 
and indications of the appearance of a lumen are found. In 
other larvae of this same stage the lumen of the body-cavities 
is quite large and the walls, therefore, well separated from one 
another. 
