512 ARTHUR WILLIAM MEYER 



double in some places lay in the media quite close to the lumen 

 of the hypogastric artery but separated from the latter by a 

 distinct although thin layer of fibrous connective tissue. As 

 shown in figure 17 (6) this elastic membrane was folded so strongly 

 in some places as to form a large accumulation of loops or coils 

 somewhat similar to, though more pronounced than, those 

 pictured by Henneberg in the extra-umbilical portion of the vein 

 of a human fetus. In addition to th"s very evident elastic 

 membrane numerous very long, tortuous and thick elastic fibers 

 (c) were also distributed throughout the media in far larger 

 numbers than found by Henneberg in the human hypogastric 

 vessels. 



Aside from possible specific differences the more pronounced 

 folding of the elastica interna and the greater tortuousness and 

 thickness of the elastic elements in these specimens as com- 

 pared with those found by Henneberg in man may, of course, 

 be due to the fact that the latter used specimens from com- 

 paratively younger individuals. The extremely folded condition 

 of the elastica in these atrophic vessels and in contracted vessels 

 as well, seems to suggest that the range of contractility and of 

 elasticity of the intima is a rather limited one. Hence when 

 this limit is exceeded by the contracting and atrophying muscula- 

 ture of the media it is folded and re-fo!ded passively. Since the 

 elastica is apparently well-preserved after the musculature and 

 intima have already begun to degenerate it can usually be stained 

 without difficulty by special methods although the failure to 

 detect it in all routine Van Gieson stains might seem to indicate 

 that it disintegrates earlier than the media. It is particularly 

 evident in sections stained with an aqueous solution of fuchsin 

 and mounted in glycerine or by the orcein-fuchsin method of 

 Unna, both of which methods also reveal numerous tortuous 

 elastic tissue fibers scattered throughout the media. 



Most of the hypogastric arteries examined had a structure 

 in marked contrast to that of the unpaired portions of the um- 

 bilical vein. However, their structure is identical with that of 

 the unpaired vein in so far as no elastica interna was usually 

 noticed, in the presence of a single-layered endothelium and a 



