326 The Alligator and Its Allies 
(sc) is here differentiated into three areas—a 
dense, deeply stained area immediately around 
the neuroccel; a less dense area of cells surrounding 
the inner area and extending ventralward as a 
rounded projection on each side; and an outer 
layer, with few or on nuclei, surrounding the inner 
two layers except on the dorsal side. 
In Figure 202 the size and complexity of the 
figure are due, it will be easily understood, to the 
fact that the plane of the section passed through 
the curve of the body, thus practically cutting 
the embryo in two regions—an anterior, where the 
lungs (Ju) and liver (Ji) are seen, and a posterior, 
where the Wolffian bodies (wf) are present. The 
spinal cord and the surrounding structures have 
almost the same characteristics at both ends of the 
figure, except that the primitive spinal column is 
rather more distinct in the posterior end of the 
section. The posterior cardinal veins (pc), Wolf- 
fian ducts (wd), and Wolffian bodies (wt) are also 
prominent structures of this end of the figure, 
the last being made up of a great number of tubules. 
The extreme anterior ends of the Wolffian bodies 
are seen in the other half of the section in the upper 
angles of the body cavity, dorsal to the lung rudi- 
ments (Ju). Filling most of the body cavity (bc) 
and making up the greater part of the middle of the 
figure are the liver (Jz), now a very large organ; the 
stomach (z’), also quite large; the pancreas (pan), a 
small body lying near the stomach; and the lungs 
