BveTuupellide 33 
well down into the thoracie cavity in relation to the base of the heart 
where it has fused with the gland of the opposite side. Buds are now 
beginning to form through the greater part of its extent. Traces of the 
original lumen (/) may still be seen in several places. The “thymus 
superficialis ” is bent around the twelfth nerve. A delicate cord of thymic 
Texr Fie. 5. 
TEXT FIGURE 5. Ventral view of thymic anlage; X 33; pig embryo, 27 mm.; 
f, area fused with gland of opposite side; 7, lumen; nt, nodulus thymicus; 
th, thoracic segment; ts, thymus superficialis. 
tissue fused with the back of the nodulus thymicus connects the thymus 
superficialis to the rest of the head. 
From about 3 cm. until toward the end of fcetal life the thymus shows 
the two constrictions, described by Prenant (22) (for the sheep) as the 
intermediary and the cervico-thoracic cords. These cords connect three 
ey 
