("han(;es in fetal vessels of the liner 511 



muscle libers spoken of by Herzog are said to l)e disposed longi- 

 tudinally or transversely, those extending in both directions 

 lying adjacent and interlacing with each other. Herzog found 

 no elastica interna and no elastic tissue present in man and 

 Haui:)tmann reported shnilar results for the vein in the cord of 

 the colt. The last author also stated that a strongly developed 

 adventitia was present in the developing artery but at no stage 

 in the development of the vein which was said to he in loosest 

 connection with the surrounding tissues. 



It is interesting that Haberda stated that all authcjrities are 

 agreed that elastic tissue is sparse in the extra-abdominal portion 

 of the hjq^ogastric arteries and that even in their intra-abdominal 

 portions less is found than in other arteries. Lochmann, on the 

 contrary, who also worked with human material found an elastica 

 interna present in all vessels and reported the formation of a new 

 media in one case. However, Henneberg insists that Lochman's 

 methods were not wholly reliable. 



Although no special methods for demonstrating the ])resence 

 of elastic tissue were used in every instance the presence of 

 numerous elastic fibers in the distal extremities of several of the 

 retracted hypogastric arteries of the sheep was unciuestioned 

 in specimens stained with Van Gieson even. They were not 

 noticed regularly in sections of vessels from other animals stained 

 in this way, however, and nothing that suggested the ]:)resence 

 of a complete elastica interna was noticed save in some sections. 

 Although occasionally very evident, it was seldom co-extensive 

 with the perimeter of the vessel but was noticeable on'y in small 

 areas. Moreover, shice the elastica interna was usually per- 

 fectly evident in sections stained with Van Gieson, in ^•ery much 

 smaller arteries that lay in the nighborhood, it is to be doubted 

 whether it is invariably i)resent in the peripheral portions of 

 the hypogastric arteries even. Although allowance nmst be 

 made for the effect of degenerative changes this supposition is 

 further confirmed by the use of special stains such as Unna's 

 orcein and fuchsin and Weigert's elastic tissue stain. In a speci- 

 men from a lamb 5^ weeks old so stained a su])risingly well- 

 developed and extremely folded elastica iiitenm which was 



