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 



MULLER first discovered 

 certain glandular epithe- 

 lial tracts in the floor of 



"" cc the atrial chamber in its 

 n-c 



hinder portion. These 



cellular thickenings are. 

 distinguished by their 

 high cylindrical cells from 

 the flattened atrial epi- 

 thelium which surrounds 

 them. (Cf. Figs. 1 1 and 

 26.) Johannes Muller sug- 

 gested that these groups 

 of cells might be renal 

 organs. His observation, 

 however, failed to find 

 general acceptance among 

 morphologists for ;'bout 

 thirty-five years, when, 



' m l ^7^> W. R 



etc 



Zm~ 



Fig. 26. Transverse section through 

 post-pharyngeal region of young individual, p AUL LANGERHANS, WOrk- 

 to show groups of renal cells in floor of 

 atrium. (After LANKESTER and WiLLEY.) ing independently, fully 



ao. Aorta, at. Atrium, b.c. Bodv-cavity ., , . 



(ccelom). c.c. Central canal of nerve-cord Confirmed hlS ECCOUH 

 (.c). d.f.c. Fin-cavity. i.m. Intercoelic am j accep ted his inter- 

 membrane. /.;. and r.m. Left and right 



metapleural folds, r.p. One of J. Muller's pretation of the bodies as 

 renal papillae, s.i.v. Sub-intestinal vein. , , u 



renal organs, at the same 



time adding a careful histological description of them 

 (Fig. 27). 



