THE EXCRETORY SYSTEM 



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stance of the kidney, and the spermatozoa are carried through 

 this organ to the ureter, which thus serves also as a vas 

 defer ens. The 

 vasa efferentia are 

 originally out- 

 growths of the 

 walls of the Mal- 

 pighian corpus- 

 cles which be- 

 come connected 

 with the testis. 

 In some species 

 (R. esculenta) 

 the Malpighian 

 bodies, which give 

 rise to these out- 

 growths, still pre- 

 serve their original 

 function, and dur- 

 ing the period of 

 sexual activity 

 spermatozoa may 

 be seen in them 

 as well as along 

 the whole length 

 of the renal tu- 

 bules which arise 

 from them. The 

 vasa efferentia 

 lead into a longi- 

 tudinal canal (Bidder's canal) which runs near the median 

 edge of the kidney. 



In Ranafusca, according to Beissner, this canal is con- 



