56 



ANATOMY OF AMPHIOXUS. 



of the peculiarities of its organisation. Thanks, however, 



to recent researches, it is now known to possess such 



organs in luxuriant abundance. 



From first to last several entirely different structures 



have been credited with a renal function. Johannes 



MiJLLER first discovered 

 certain glandular epithe- 

 lial tracts in the floor of 

 the atrial chamber in its 

 hinder portion. These 

 cellular thickenings are 

 distinguished by their 

 high cylindrical cells from 

 the flattened atrial epi- 

 thelium which surrounds 

 them. (Cf. Figs, ii and 

 26.) Johannes Miiller sug- 

 gested that these groups 

 of cells might be renal 

 organs. His observation, 

 however, failed to find 

 general acceptance among 

 morphologists for about 

 thirtv-five years, when, 



Fig. 26. — Transverse section through "'' 1S76, W. ROLPH and 

 post-pharyngeal region of young individual, p^uL L\NGERHANS WOrk- 

 to show groups of renal cells in floor of ' ' " ' ' ' 



atrium. (After L.-iNKESTER and \\'iLLEY.) ing indcpendcntlv, fully 



ao. Aorta, at. Atrium, b.c. Bodv-cavitv "" - i 1 • 



(cffilom). C.C. Central canal of netve-cord Confirmed hlS aCCOUnt 



f^.d. rf./<:. Fin-cavity. i.m. Intercoelic ^^d accepted his inter- 

 membrane, l.m. and r.vi. Left and right ^ 



metapleural folds, r.p. One of J. Muller's pretation of the bodics aS 

 renal papillfe. s.i.v. Sub-intestinal vein. , ^ ^, 



renal organs, at the same 

 time adding a careful histological description of them 

 (Fig. 27). 



