68 DEVELOPMENT OF THE LYMPHATICS OF THE LUNGS IN THE EMBRYO PIG. 



Plate 4. 



Fig. 1. Longitudinal section of the left lunj; of :in embryo pig 5 oin. long, in wliicli tlio lynipliatics were injected with 

 pru-ssian blue throuKh the retroperitoneal sac. The veins have some blood pigment in them. The 

 section is 4(X)m tliick ami is un.stained. X2'2. V, vein. 



Fig. 2. Dissection of an embryo |>ig 4 cm. loii};. in which the lynipliatics were injected with prussian blue from tlic 

 retroperitoneal sac. The right lung, esophagus, and body-wall have been removed. The stomach 

 was pulled to the left side of the embryo in order to expose the retroperitoneal sac. Cleared by the 

 Spalteholz method. X20. Ao, aorta; L L, left lung; Th D, thoracic duct; I), diaphragm; H I' S, retro- 

 peritoneal sac; *, first vessel to the lung. 



Plate 5. 



Fig. 1. Surface of lung of an embryo pig 23 cm. long, in wliich the lymphatics were injected with prussian blue, by 

 puncture of an interlobular septum. Cleared by Spalteholz method. The interlobular septum is indi- 

 cated by a very large lymphatic trunk. X28 / L S, interlobular septum. 



Fig. 2. Longitudinal section of the upper portion of the lower lobe of the left lung of an embryo pig o cm. long, in 

 which the lyiM])hatics were injected with prussian blue through the retroperitoneal sac, and the veins 

 have retained a little blood iiigment. The section is 400^ tliick and is unstained. X57. 1', vein; 

 A, artery; /■'/, pleura; B, brondius. 



Fig. 3. Lower portion of left lung of an embryo pig 5 cm. long, in whidi the lymphatics were injected with india ink 

 through the retroperitoneal sac. Cleared by the Spalteholz method and mounted in balsam. X28. 



