With adult rabbit under nembutal anesthesia they were subjected to laparotomy, and after ligating chylus about 10ml of India ink diluted 4-fold with physiological saline solution was injected slowly into inguinal lymph nodes and external iliacal lymph nodes. About 5 hours later the abdominal aorta was taken out, and it was cut into longitudinal and cross celloidin sections of about 100μ in thickness, which were stained with aldehyde-fuchsin or light-green solution and the distribution of lymph vessels in the arterial wall was observed. With some of the above specimens transparent samples were also prepared. By the forced reverse flow of lymph it was found that the excretory lymph vessel group arising from lymph capillary immediately adjacent to the internal elastic membrane of the aortic wall runs gradually along collagenous fibers through the fenestrations of each elastic membrane of the tunica media, and appears at the tunica adventitia and after confluencing they become a ralatively large excretory lymph vessel, but they further confluence with the excretory lymph vessel arising from the lymph capillary of fat tissue in the tunica adventitia, and they form an aggregative lymph vessel which runs over the exterior layer of the tunica adventitia, and when it comes out of the tunica adventitia it enters into the aortic lymph node.
What is noteworthy is the fact that both the aggregative and excretory lymph vessels have peri-lymphvessel spaces. Embryologically, such a peri-lymphvessel space is a kind of closed space formed by the peri-arterialwall connective tissue consistig of double membrane that covers a part of the aortic lymph nodes to make an aggregative lymph vessel, and then excretory lymph vessel, which should be considered as a lymph space. Further at the site where the aggregative lymph vessel come in this closed space there is a narrow gate.