138 GEO. S. HUNTINGTON 
cept of the early phylogenetic type of bronchial unfolding. If 
the right eparterial and cardiac bronchi of the prevalent type 
were primarily derivatives of the first ventral bronchus, the for- 
mer a dorsal, the latter a ventro-medial branch, and if in the 
rest of the series all dorsal, dorso-medial, and ventro-medial 
components of the stembronchus were originally derivatives from 
the primary ventro-lateral bronchus of their respective levels, 
then these premises would define the most primitive mammalian 
or promammalian stem-bronchus as giving origin solely to mon- 
opodic ventro-lateral derivatives, whose secondary branching 
Fig. 44 Hypothetical plan of the primitive derivatives of the stem-bronchus, 
as stipulated by the Migration Theory. 
carries their distribution into the remaining dorsal, dorso-medial 
and ventro-medial districts. The schematic cross section of a 
hypothetical reconstruction of this bronchial type would appear 
as in figure 4“. Migration then becomes responsible for the re- 
distribution of the components shown in figure 4”. 
The pulmonary organization represented in figure 4* is not 
found in the phyletic series. 
If this is accepted as indicating the earliest phylogenetic mam- 
malian type of bronchial organization, one of two conclusions 
would be inevitable: 
a. Either the mammalian lung represents the persistence of a 
more primitive pulmonary type than that found in the embryo 
or adult of any of the extant lower vertebrates, or 
