164 GEO. S. HUNTINGTON 
predecessor, the primitive entodermal lung-tube, of developing 
lateral buds from any point of its circumference. 
2. In the mammal these points of epithelial sprouting tend to 
arrange themselves mainly in a ventro-lateral and a dorsal 
Fig. 8 Schema showing numerical variation in the primary derivatives of 
the stembronchus and its results in the resulting peripheral areas of distribution. 
longitudinal row. The former are the larger and expand further 
toward the periphery, the latter are smaller and less extensively 
developed. They constitute the ventral and dorsal primary 
branches of the stembronchus, and form with it the foundation 
of the bronchial tree. Hence the stembronchus acquires a dorso- 
