112 The Development of the Lungs 
dichotomy,” his own description of the process of division appears to me 
to be esentially of a monopodial character. Against these views we have 
the outspoken description of Minot for dichotomy, in the human lung, 
as well as that of Blisnianskaja. The latter does not describe the process 
in detail and her illustrations appear to me to be capable of a monopodial 
interpretation, especially in view of the careful work of His on the same 
material. It is also noteworthy that she quotes the statements of Juste- 
sen in supporting her ideas on the sympodial development of the chief 
divisions of the stem. It may be recalled, however, that this author did 
not possess in his material stages which showed the development of these 
particular branches. 
While it is possible to draw much harmony from the verbal descrip- 
tions of the process of division which I have given above, there are, of 
course, many exceptions and different complexions to these views. Since, 
in my opinion, it makes little difference whether the monopodial out- 
growths take place from the end bud or from the stem a little higher 
up, we may justifiably say that among those who have studied the pro- 
duction of the chief bronchi of the vertebrate lung, the following stand 
for an absolute monopodial system: Moser, Hesser, Schmalhausen, His, 
Wilach, Robinson (?), @Hardiviller, Nicholas and Dimitrova, Narath, 
and Flint. ‘This series includes obviously all who have worked on the de- 
velopment of the lung during this period except Minot, Blisnianskaja, 
and Robinson, whom I have placed in both lists. Of these authors, Wil- 
lach, Narath, Minot, and Blisnianskaja believe that our Lateral 1, the 
so-called ‘ Eparterial or tracheal bronchus,” is a derivation of our 
Lateral 2, which wanders up on the stem bronchus or trachea, the others 
look upon it as an independent and unpaired element. Narath and 
Blisnianskaja regard the other chief bronchi as secondary derivatives of 
the lateral group as “ accessory ” in the sense of Aeby. Willach believes 
the ventral and median groups as accessory, that is to say, derived from 
the lateral and dorsal bronchi respectively, while Robinson thinks the 
chief bronchus of the ventral series, Ventral 2 (the Bronchus infra- 
cardiacas) is ontogenetically independent, but phylogenetically accessory. 
The latter describes the origin of the medial bronchi, his dorsointernal 
group, from the dorsal by a process of progressive splitting of the first 
medial branch of the dorsal bronchi until it comes to have an independent 
origin on the stem, a view which is advanced in greater detail by Narath. 
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 
