ee 
Nachdruck verboten. 
The Development of the Lungs in the Pig. 
(Preliminary Note.) 
By JoserH MarsHaut Fiint, M.D., 
Professor of Anatomy in the University of California. ~ 
By means of a series of wax plate reconstructions, corrosions, 
injections, and sections of the lungs at various ages, the writer has 
followed the development and organogenesis of the lungs. Although 
a detailed account of these observations will appear in another place, 
the following conclusions will serve to communicate the general re- 
sults obtained. 
1. The anlage of the lungs in the pig is unpaired and asymme- 
trical. It arises from the ventral part of the head gut behind the 
Sinus venosus, as a ventral out-growth, preceded by a lateral flattening 
of the foregut below the gill pouches and the appearance of longitu- 
dinal furrows, which divide it into two parts, a ventral respiratory 
portion, and a dorsal digestive segment. From the lower part of the 
pulmonary anlage, the lungs arise, from the upper, the trachea. If 
there is a serial phylogenetic association between the pulmonary anlage 
and the gill pouches, as some authors maintain, the connection is lost 
in the pig, for the lungs originate well below the gill area and dis- 
tinctly ventralwards to the series of bronchial pouches. From the 
caudal extremity of the pulmonary anlage, arise two lateral outgrowths, 
giving rise to the stem bronchi. These like the anlage itself are 
asymmetrical, the right growing lateralwards and caudalwards, while 
the left extends almost directly horizoutal. Then the respiratory and 
digestive portions of the head gut begin to separate, a process, which 
begins from the caudal end of the anlage and extends upwards along 
the line formed by the two longitudinal furrows, gradually freeing the 
respiratory apparatus from the oesophagus. In its subsequent growth, 
the pulmonary anlage enlarges, the tips of the stem bronchi dilate, 
and begin to bend dorsalwards around the oesophagus. This results 
in the formation of the primitive lung sacs. At this time, the pro- 
duction Of the bronchi begins. They are readily divided into four series 
from the topography of their origin, namely; lateral, dorsal, ventral, 
and medial. 
