176 MERISTIC VARIATION. [part i. 



determined in comparatively few instances. In a case dissected by 

 Neuhofer 1 there was a fistula on each side, the external opening 

 of the right was ^ in. from the middle line and 7 lines above the 

 clavicle, that of the left was 3 — 4 lines higher and further from the 

 middle line. The right internal opening was on the posterior border of 

 the pharyngo-palatine muscle, behind the cornu of the hyoid near the 

 tonsil, the left internal opening being rather higher than the right. 

 Internal openings of such fistula? have also been seen on the edge of 

 the arcus pharyngo-palatinus, also in the neighbourhood of the root of 

 the tongue. Seidel 2 gives a case in which there were two fistulas, the 

 one on the right side in the upper position, and the other in the middle 

 line at about the same level, but whether either of these communicated 

 with the pharynx could not be made out. The twin-brother of the 

 same infant had a single minute fistula. 



The ducts of cervical fistula? are usually of greater calibre than the 

 external openings but they are rarely wider than a fine quill. The 

 walls are tough and the lining epithelium is sometimes flat and some- 

 times ciliated. The degree to which the walls are sensitive differs in 

 different cases. The external opening is described in several instances 

 as having a reddish colour. In three cases of the presence of branchial 

 fistula? in female patients, it is recorded that the external openings 

 became inflamed during the menstrual periods. 



From the point of view of the naturalist the chief interest of 

 cervical fistula? arises in connexion with the question of their mor- 

 phology. Since the time of Ascherson the view has been commonly 

 accepted that these structures arise by persistence of embryonic gill- 

 clefts, and some of the recent writers 3 on the subject have gone so far 

 as to apportion the various forms of cervical fistula? among the several 

 gill-clefts from the first to the fourth, according to the situations of 

 the external openings, giving diagrams shewing the regions occupied by 

 each. As Kostanecki and Mielecki point out, this apportionment is 

 quite arbitrary; for in the development of the neck the external in- 

 vaginations for all the clefts behind the hyoid arch become included in 

 the sinus cervicalis of Rabl (sinus pra?cervicalis of His), which is 

 eventually closed by the growth of the opercular process from the 

 hyoid arch. The external opening of a cervical fistula may thus 

 represent a part of the sinus cervicalis still left open, but it cannot on 

 the ground of its position be referred to any gill-cleft in particular. 

 Such reference could only be properly made on the ground of the 

 position of the internal opening and the course of the duct in relation 

 to structures whose relation to the visceral clefts is known. More- 

 over owing to the way in which the 3rd and 4th clefts are shifted 

 inwards by the formation of the sinus cervicalis, Kostanecki and 

 Mielecki consider that they are practically excluded. The same 

 authors after an analysis of the cases in which the position of the 

 internal opening has been properly ascertained, come to the conclusion 

 that in all these it falls within the region of the 2nd visceral sac 



1 Neuhofer, M., Ueb. d. angeb. Halsfistel, Inaug. Diss., Munich, 1847. 



2 Seidel, J., Defist. colli congen., Inaug. Diss., Breslau, 1863. 



3 Sutton, J.Bland, Lancet, 1888, p. 308; Cusset, Etude sur I'appareil branchial, 

 &c, Paris, 1887. 



