259 



But early in our study we encountered an iliac artery in the 

 media of which were very definite oblique and longitudinal bundles 

 of muscle fibres. 



Was this an individual arrangement of the fibres — a mutation — 

 or had it any deeper significance? Examination of sections made 

 from other iliac arteries showed that they present similar bundles, 

 and it was found that they did not extend the whole length of the 

 artery, but were present at the region of greatest curvature. From 

 the occurrence of these oblique and longitudinal muscle bundles in 

 the walls of the iliac, as it bends over the brim of the pelvis and is 

 subjected to more less constant bending to and fro, it seemed worthy 



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Fig. 3, Longitudinal section from the same artery which is represented in 

 Fig. 1, showing the circularly ari'anged fibres of the media cut transversely, and the 

 reinforcing bundle cut more or less longitudinally. 



of investigation to observe such arteries as are peculiarly subjected 

 to bending and stretching; to determine whether these in the region 

 of curvature also exhibit the oblique and longitudinal bundles; to 

 determine in short, whether such bundles signify reinforcement in 

 regions of strain. It is significant that, as a matter of fact, I find this 

 to be the case. Selecting the common iliac, the popliteal, and the 

 brachial arteries, up to the present out of sections made from different 

 portions of 12 iliac arteries, from different regions of 6 popliteal 

 arteries, and from 5 brachial arteries taken at the elbow, in every 

 case these oblique and longitudinal fibre bundles have been found 

 in some portion, apparently limited to between 3 to 5 cm., along 



17* 



