474. WILLIAM SNOW MILLER 
TERMINAL BRANCHING OF THE BRONCHI 
Although the main series of bronchi divide monopodially, the 
mode of division, as shown in the reconstruction, is quite differ- 
ent in the terminal divisions. Other investigators have also noted 
a difference. 
Ewart says “‘strictly dichotomous branching predominates in 
the end branchings of the bronchial tree.”’ 
d’Hardiviller, in his description of the finer air passages, says 
that each bronchiolus respiratorius divides into two or more 
canals which show, on their part, several bifurcations. 
His describes the primary bronchi as dividing in a monopodial. 
manner but says that further growth takes place through the 
dichotomous fission of the end bud. Robinson reached similar 
conclusions. 
Justesen studied the mode of branching of the bronchial tree 
both in the embryo and in the adult and he finds that in all the 
branches, from the largest to the smallest, the mode of division 
is exclusively dichotomous. 
Flint believes in a monopodial division for the main series, 
but finds that subsequent division may be either by monopody 
or dichotomy. In some instances there may be alternation of 
the two processes. : 
With the possible exception of Flint, none of the investigators 
who have studied the smaller bronchi seem to have found any- 
thing but dichotomous branching. It is certain, however, that 
in the portion of the lung of the cat entering into the reconstruc- 
tion dichotomy does not uniformly prevail. From the bron- 
chiolus two branches arise and each of these divides into two; with 
this division dichotomy ends. From this last division three duc- 
tuli alveolares of practically the same size and length arise. Two 
of these ductuli alveolares have each three atria attached to 
them while the third has four; of the ten atria, four have two sac- 
culi alveolares arising from each, three have each three sacculi 
alveolares attached to them, two have four sacculi alveolares 
each, while one has five sacculi alveolares arising from it. 
(as 
