Florence E. Sabin 



191 



over the shoulder of a pig 5 cm. long. It will be noted that there is a 

 clear differentiation between the choriiim and the subcutaneous tissue. 

 In the chorium the protoplasmic network is fine and closely meshed, while 

 the subcutaneous tissue is more fibrillar, the tissue is more open or the 

 spaces are larger. The lymphatics are large and lie in the border between 

 the chorium and subcutaneous tissue. The blood capillaries are small 



FiQ. 6. Transverse section of the skin of the shoulder of a pig 5 cm. long showing 

 the primary lymphatics. About X 110. he; blood capillaries; c, chorium; I, lympha- 

 tics ; st, subcutaneous tissue. 



and lie both in the subcutaneous tissue and in the chorium. All of the 

 vessels within the chorium are confined to its inner half. 



From this time on. until the embryo is 6.5 cm. long, the lymphatics 

 gradually spread over the entire body in a single layer of ducts. These 

 ducts make a characteristic plexus, as shown in Fig. 5. The plexus has 

 been described and illustrated in the paper cited above. The growth of 

 the ducts within the plexiis has been described by Eanvier " and by Mac- 



^Ranvier: Comptes Rendus, 1895 and 1896. Archiv d'Anatomie, 1897. 



