144 GEO. S. HUNTINGTON 
He further states (21, pp. 112, 113): 
All of the arguments of Narath and Blisnianskaja concerning the 
derivation of the ventral, dorsal, and medial series either primarily 
or secondarily from the lateral bronchi are quite unconvincing, for like 
the support, which Narath brings from the comparative anatomy, the 
facts are capable of a simpler explanation, i.e., a wide variation in the 
position of the buds and the power of one bronchus substituting for 
another. 
The comparative anatomical facts adduced by Narath further 
demonstrate that the dorsal pulmonary areas may receive their 
conducting tubes from any accessible point of the adjacent bronchial 
tree within their range. This is the important conclusion, whose 
significance will be discussed presently. The Migratory Theory 
suffers from a grave constitutional defect. It has become so 
imbued with the mechanical aspects of its problem that the naked 
corrosion cast of the bronchial tree assumes the proportions of a 
morphological unit, complete in itself and to be judged as such. 
It is a tree stripped of its finer twigs and leaves, the unfolding of 
which is the primary physiological purpose of the entire structure. 
A lung corrosion in which the injection has been carried into the 
respiratory bronchioles and alveolar spaces corresponds to the 
tree in full leaf. In both the same degree of unfolding of an 
equal respiratory surface can be accomplished by grouping the 
elements of the conducting and supporting skeleton in a variety 
of mechanical patterns. The tree has the larger range of varia- 
bility in the number and disposition of the individual leaf buds, 
but the bronchial system, though reduced in potential excursion 
by the physical environment, follows absolutely the same mor- 
phogenetic plan. 
It is at times difficult, especially in the caudal pulmonary areas, 
to select from among the irregularly disposed dorsal bronchi the 
proper individual element supposed to belong genetically to a 
given ventral bronchus. Narath himself recognizes this when he 
says (33, p. 306), “‘ Die Orientirung wird dann ungemein erschwert 
und manchesmal ist iiberhaupt eine sichere Bestimmung des 
Bronchus unméglich.”’ 
