THE UMBILICAL CORD. 



373 



and eosin, or with Heidenhain's iron hehiatoxylin and orange G; or, if it is 

 desired to study the development of the connective-tissue fibrillae, with Mallory's 

 triple, connective-tissue stain. 



FIG. 255. CROSS-SECTION OF A HUMAN UMBILICAL 

 CORD AT TERM. 



.4, A', Umbilical arteries much contracted. V, Um- 

 bilical vein. Y, Remnant of allantois. X 12 

 diams. 



FIG. 256. SECTION OF THE ALLANTOIS FROM A 



HUMAN UMBILICAL CORD OF THREE MONTHS. 



ent, Allantoic entoderm. mes, Mesoderm. X 340 



diams. 



FJG . ^.CONNECTIVE TISSUE FROM THE UMBILICAL CORD OF A HUMAN EMBRYO OF 21 MM. STAINED WITH 



ALUM COCHINEAL AND EOSIN. 

 n, Nucleus, p, Protoplasmic network. X 540 diams. 



A general description of the umbilical cord has been given, pages 115 to 116, 

 and two sections (Fig. 66) are there represented showing the structures which 

 appear in sections of the umbilical cord. At full term some of these structures 



