154 CONVERGENCE IN MINUTE STRUCTURE 



latter in 1892. Attached in clusters to the 

 walls of the tubules Boveri found long pin- 

 shaped cells, which he called " Fadenzellen " 

 (thread-cells), projecting into the dorsal coelom. 

 They appeared to consist of a small roundish 

 cell-body mounted upon a long thread-like stalk 

 which was inserted into the tubule. Ten years 

 later Goodrich, who had been making some 

 notable discoveries in regard to the structure of 

 the nephridia of Polychsete worms, turned his 

 attention to the tubules of Amphioxus and 

 promptly discovered that Boveri's thread-cells 

 are identical with the solenocytes which he had 

 found in Polychaeta. 



Goodrich showed that Boveri's thread - like 

 stalk is really a slender hollow tube of great 

 length, carrying the cell - body floating in the 

 coelom, or adhering to the adjacent walls of 

 the coelom, at its distal end, and opening into 

 the renal tubule at the proximal end. " A long 

 flagellum attached at its base to the cell placed 

 at the end of the tube works rapidly down the 

 tube and far into the excretory canal." 1 Goodrich 

 observes that the excretory organs of Amphioxus 

 and the nephridia of Phyllodoce are in all essentials 

 identical, and he adds that " if two such excretory 

 organs as the solenocyte - bearing nephridia of 

 Phyllodoce, and the solenocyte-bearing kidneys 



1 E. S. Goodrich, "On the Structure of the Excretory Organs of 

 Amphioxus," Part i., Quart. Jour. Micr. Sc.^ vol. xlv., 1902, pp- 

 493-501 ; Part ii. Ibid. vol. liv., 1909, pp. 185-205. 



