80 The Development of the Lungs 
superior on the right side (Fig. 18, L. 1) is now pushed dorsalwards 
by the presence of the heart and the Lobus medius (Fig. 18, L. 2), so that 
its caudal portion now hes above the series of swellings over the dorsal 
bronchi (Fig. 18 6, D. 2). On the left side, the Lobus superior now 
shows a dorsoapical swelling over the apical branch of L. 2 (Fig. 18, 
L. 2), which indicates the beginning of the portion of the left upper lobe, 
which substitutes for the Lobus superior on the right side. The fissure 
between L. 2 and L. 3 on each side deepens, while the Lobus inferior on 
both sides shows a series of projections over the several branches of the 
stem. On the ventral surface, V. 3 is indicated; on the lateral border, 
Tuxr Hie 9: 
TExT Fic. 19. Outline drawing of the lungs of an embryo pig 18.5 mm. 
long. A. Ventral view. B. Dorsal view. The abbreviations on the swellings 
represent the order of the bronchi beneath. Designations as in Fig. 16. 
L. 3, L. 4, and L. 5; while, on the dorsal border, swellings for D. 2, 
D. 3, and D. 4 are present. 
In a pig 18.5 mm. long (Fig. 19), the right Lobus superior contain- 
ing Lateral 1, projects upward some distance beyond the tip of the upper 
lobe on the left side. The fissure separating it from the Lobus medius 
has deepened. Its lower portion now passes behind the medial lobe, 
although the two are united at their roots, that is to say, the ventro- 
medial aspect. The Lobus infracardiacus projects ventralwards and 
medialwards until it extends over the median line above the cesophagus. 
The lower lobe on the right side shows projections along the lateral 
border for L. 3, L. 4, and L. 5, and, on the dorsal border, for D..2, D. 3, 
and D. 4. The ventral surface, likewise, has very slight swellings for 
