ranviee's constrictions in the spinal cord. 91 



The Presence of Ranvier's Constrictions in the 

 Spinal Cord of Vertebrates. 



By 



Dr. '%Villiatn Toimsend Porter, 



of St. Louis. 



With Plate XII, bis. 



No question in the controversy over Ranvier's constrictions 

 is more interesting than that of distribution. Torneaux and 

 Le Goffi declared in 1875 that constrictions are present in 

 the spinal cord. Their discovery remained almost unnoticed 

 until Schiefferdecker^^ not aware that he had been anticipated 

 by the French observers, offered silver pictures as proof that 

 the constrictions are not confined to the peripheral nerves. 

 The statements of these authors have been contested. BolF 

 wrote against Torneaux and Le Goff; and Kolliker/ seeking 

 to test the results of Schiefferdecker, worked over the same 

 ground, but arrived at opposite results, and brought new argu- 

 ments in favour of the old opinion. 



It is of importance to have this question examined by many 

 observers, for the presence of constrictions in the spinal cord 



1 "Note sur les etranglements des tubes nerveux de la moelle epiniere," 

 ' Journal de I'Auatomie,' 1875. 



2 "Beitrage zur Kenntniss des Baues der Nervenfasera," 'Arch. f. mikr. 

 Anat.,' Bd. xxx, 1887. 



3 "Ueber Zersetzungsbilder der markhaltigen Nervenfasern," 'Arch, f, 

 Anat. u. Entwickelungsges.,' 1877. 



* 'Handbuch des Gewebelehre des Menschen,' Leipzig, 1889, Bd. i, p. 

 154. 



