48 Florence R. Sabin. 



Between the years 1895 and 1897, Eanvier published a series of 

 articles on the development of the lymphatic system. ''' He also 

 studied the development of the lymphatic system in the frog and 

 added an extensive study of the growth of the lymphatics in pig 

 embryos from 9 to 18 cm. long. He observed endothelial sprouts 

 in growing lymphatics and interpreted them as Langer had done 

 27 years before to mean that the growth of the lymphatic capillaries 

 is by the process of sprouting. Some of the very large lymphatic 

 vessels which he found in the mesentery he interpreted to mean 

 degeneration or retrogression of the system. Eanvier suggested the 

 theory that the lymphatic system comes from the veins, on the basis 

 that the growth is from centre to periphery rather than from the 

 connective tissue spaces to the veins — but he did not prove his theory, 

 for he did not find lymphatics in embryos below 9 cm. in length, at 

 which time the lymphatic capillaries have already covered the surface 

 of the body. 



W. J. MacCallum was the next one to call attention to this method 

 of growth by sprouting and he has given graphic descriptions of the 

 process. He studied developing lymphatics in the skin of embryo 

 pigs, 5 to 15 cm. long, watching the injection under the microscope 

 in order to determine the relation of the lymphatic capillaries to the 

 connective tissue cells and spaces.^ 



In studying the growth of the lymphatic capillaries in the skin 

 of the embryo pig, I found that the early lymphatics started from 

 certain centres and gradually spread over the surface of the body.^ 

 The first of these areas is in the neck, from which vessels grow over 

 the head, shoulder and back. The second is over the crest of the 

 ilium for the vessels over the back and hip, while subsequent centres 

 form the axilla and inguinal region for vessels to the ventral aspects 

 of the body wall and limbs. By studying the figures in Volume III, 



'Ranvier. Comptes Rendus de I'Acad. d. Sciences. 1S94 to 1896, and 

 Archives d'Anatomie microscopiqne. Paris, 1897. 



'MacCallum. Die Beziehung der Lymphgefiisse zum Bindegewebe. Arch. f. 

 Anat. u. Phys., Anat Abth., 1902. 



*Sabin. American Journal of Anatomy, Vol. I, 1901-1902, Vol. Ill, 1904, 

 and Vol. IV, 1905. 



