Joseph Marshall Flint 15 
from beginning to last. He abandons the distinction between the hypar- 
terial and eparterial regions as well as Aeby’s simple nomenclature and 
substitutes in its place a method of topographical designation which, 
besides going into endless detail, is constructed entirely independent of 
embryological considerations and has received, thus far, no support from 
subsequent investigators. 
In a series of papers the first of which appeared the same year, Zum- 
stein, 89, 91, 92, 00, by the study of corrosion specimens of the lungs of 
a series of mammals and birds in which the pulmonary artery as well 
as the bronchial tree was injected is unable to support Aeby’s conclusions 
with reference to the influence of the pulmonary artery on the archi- 
tecture of the bronchial system. The division of the tree into eparterial 
and hyparterial bronchi according to Zumstein is not based on sound con- 
clusions as he finds a series of variations in both arteries and bronchi, 
indicating that a formative influence in the sense of Aeby cannot exist. 
At the same time Zumstein siudied the development of the lungs in the 
mole and the duck by the Born reconstruction method. With other in- 
vestigators, he agrees in the precocious development of the right lung 
He does not describe in detail, however, the gradual evolution of the 
mammalian lung but simply states that the dorsal and medial bronchi 
arise later than the lateral branches but do not attain the extensive de- 
velopment of the latter. Whether or not he considers them accessory 
bronchi in the sense of Aeby is not clear from his description. The 
Bronchus infracardiacus may originate, according to Zumstein, either 
from the stem bronchus beneath the second lateral bronchus or from this 
bronchus itself. The eparterial branch of Aeby he designates as the first 
lateral bronchus. In the early stages the Arterie pulmonales originate 
far cranialwards and accompany the trachea ventro-lateralwards on both 
sides. The left is more dorsal even before the trachea is reached while 
the right artery passes ventralwards of the first lateral branch of the 
right bronchus (Aeby’s eparterial). It is scarcely possible, Zumstein 
concludes, for the arteries to have an influence upon the structure of the 
tree as the first bronchi have appeared on the stem bronchus before the 
arteria pulmonalis can be traced into the lung. 
In a preliminary note Narath, 92, published a résumé of a large 
monograph upon the embryology and comparative anatomy of the bron- 
chial tree of the mammalian lung, which appeared some nine years later, 
o1. Before this work was published, however, Narath, 97, described the 
development of the lung in Echidna aculeata. In all of the papers, he 
takes exception to Aeby’s fundamental conception of the architecture of 
the bronchial tree. From a rich embryological material, echidna, rab- 
