Joseph Marshall Flint 19 
and a ventral, originate in the form of buds upon the bronchial stems. 
Each is an independent structure and does not show any ontogenetic 
relationship with the other bronchi, indicating a wandering of the acces- 
sory bronchial groups as described by Aeby, Willach, and Narath or 
d’Hardiviller, in the case of the cardiac bronchus of Hasse. From 
the division of the first lateral bronchi, a branch passes up towards the 
head on the left side which is unpaired, for on the opposite side this 
region is supplied by the tracheal bronchus. The infracardiac bronchus, 
Nicholas and Dimitrova regard as an unpaired precocious ventral branch 
for which there is no symmetrical structure in the left lung. The 
remaining ventral bronchi appear later as in an embryo of 18 mm. they 
find one between the second and third, and another between the third 
and fourth lateral element. 
Huntington, 98, in studying the eparterial system of a series of adult 
mammals, comes to the conclusion that the right and left lungs agree 
morphologically in the type of their bronchial distribution and that 
the asymmetry is apparent and not real. These apparent differences are 
due to the shifting of a branch of the upper bronchus (cephalic trunk) 
which wanders up and becomes topographically eparterial. At times, the 
asymmetry may be more exaggerated by the migration of the entire 
branch. As the factor involved in this change is the bronchus itself and 
not the pulmonary artery, Huntington proposes to abandon Aeby’s dis- 
tinction between the hyparterial and eparterial regions of the bronchial 
tree except in a topographical sense. In the left lung there is a morpho- 
logical equivalent for every eparterial element that may occur in the 
right lung and, accordingly, this author believes in the equivalent mor- 
phological value of the upper and middle lobes of the right side with 
the upper lobe on the left. This, it will be remembered is the conclu- 
sion of Willach and Narath except that Huntington, lke Willach, does 
not believe that the eparterial element is primarily a dorsal bronchus. 
As the pulmonary artery does not run dorsal to the stem bronchus, but 
lateral, or dorsolateral, as Narath has shown, Huntington proposes 
to abandon also the distinction made by Aeby between the dorsal and 
ventral bronchi. From the study of his corrosions this author believes 
that the primitive type of division is practically dichotomous and later is 
changed into the monopodic system. Phylogenetically, the primitive 
type is the so-called bilateral hyparterial form, while the symmetrical 
eparterial type represents the end stage in the process of evolution and 
not the beginning as Aeby and Wiedersheim believe. 
An ingenious effort is made by Guyesse, 98, to support the monopodial 
theory of growth. This author has studied the transformation of the 
