282 



J. S. FERGUSON 



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Fig. 1 Transection of the ligamentum nuchae of an ox. Bielschowsky stain. 

 The ehistic fibers are colorless, the intervening tissue opaque. Camera lucida; 

 occ. 1, obj. g. 



Fig. 2 A pulmonary artery from the human lung showing the colorless internal 

 and external elastic membranes invested by blackened reticulum. Bielschowsky 

 stain. Camera lucida; occ. 1, obj. |. 



Fig. -i From a primary bronchus of man. Basement me:abrane (hm) is a dense 

 opaque black, its fibers so closely packed as to be indistinguishable. The elastic 

 fibers (ef) are colorless and are invested by a black reticulum (r). Bielschowsky 

 stain. Drawn with the Edinger projection apparatus, X 255. 



In the feiiestruted coats of the arteries one sees in the larger 

 arteries of the lungs, stomach, lymphatic glands and many other 

 organs vessels showing in the controls the typical elastic membrane 

 in the tunica intima completely encircling the vessels in transec- 

 tions. The impregnated specimens, when the same vessel is 

 examined in adjacent slides in the series, show the internal elastic 

 membrane colorless, the elastic coat in the larger vessels being in- 

 vested on either surface with a close net of black reticular fibers 

 (fig. 2). This investment of the elastic tissue by reticular fibers 

 is readily observed and is most remarkable. Similar, though less 

 numerous fibers are seen investing the elastic tissue in the inter- 

 muscular spaces of the tunica media, and in the tunica adventitia. 



