NITROGENOUS EXCRETION 



67 



Pheretima at least, the nephridia drain, not to the outside, but into 

 the gut and the absorption of protein may occur here rather than 



Nephrldiostome 



Narrow tube 



(I) 



Middle tube 



Wide tube 



Haemochromogen 

 to nepiiridial 

 wall 



Bladder 



From blood system 



Resorption to 

 blood system ? 



Fig. 21. Diagram to summarize possible mode of functioning of 

 oligochaete nephridia (Lumbricus). 



in the nephridium. Ramsay (1949b) found that whilst a consider- 

 able coagulation occurs upon heating blood from Lumbricus only a 

 very slight coagulum occurs with coleomic fluid or urine, and as 

 urine probably derives from both sources in this species the protein 



