6o 



ANATOMY OF AMPHIOXUS. 



quent excretion, the epithelium hning the walls of these 

 tubules was found to be full of carmine granules. 



At about the same time at which Weiss was pursuing 

 his studies on Amphioxus Theodor Boveri, having been 

 led by independent a priori considerations, largely induced 

 by the work of Rijckert on the development of the ex- 

 cretory system of Selachians, to suspect the occurrence 



s.ch 



Fig. 29. — Portion of transverse section through the pharynx of Amphioxus, 

 to show position of excretory tubule. (After Weiss.) 



ao. Left aorta, at. Atrial cavity, at.e. Atrial epithelium, c. Ccelom. ch, Noto- 

 chord. i.vi. Intercoelic membrane, l.d. Ligamentum denticulatum. nph. Excre- 

 tory tubule. p.b. Primary bar. pk.e. Epithelium of h}perpharyngeal groove. 

 pk.f. Pharyngo-pleural fold. sxh. Sheath of notochord. t.b. Tongue-bar. 



of excretory tubules in Amphioxus comparable to those 

 found in the embryos of the higher Vertebrates, instituted 

 a search for them and discovered them independently in 

 the most brilliant manner. 



Boveri carried his investigation to a high pitch of per- 

 fection, and has published an account of these tubules, 

 which in point of clearness and completeness leaves nothing 



