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STB[TOT[JElK OF EXCRKTORY ORGANS OP AMPHIOXUS. 493 



On the Structure of the Excretory Organs of 

 Amphioxus. 



Part I. 



By 



E<Uviii S. Ooodi-icli, M.A., 



Fellow of Merton College, Oxford. 



With Plate 27. 



The excretory organs of Amphioxus were independently 

 discovered by Weiss and Boveri in the year 1890 (1 and 13). 

 Weiss described a series of small tubules regularly dis- 

 tributed at the top of each secondary tongue-bar throughout 

 the region of the pharynx. The tubules are situated, for the 

 most part, in the wall separating the dorsal ccelom from the 

 atrial cavity ; they lie, thei'efore, between the ccelomic and 

 the atrial epithelium, generally separated from the latter bv 

 a network of fine blood-vessels. These kidney tubules open 

 into the atrium by a pore just opposite the dorsal end of the 

 secondary gill-bar. Weiss suspected the presence of an 

 internal opening, but could not find it. The physiological 

 significance of these organs he established by means of 

 feeding experiments with carmine and other colouring- 

 matters. 



In 1892 Boveri published a detailed and beautifully illus- 

 trated account of the excretory organs of Amphioxus (2). 

 In this paper such a clear and accurate description of the 

 appearance, general structure, and distribution of the 

 kidneys is given that little remains to be said on these 



VOL. 45, PART 4. — NEW SERIES. L L 



