CALCIFEROUS GLANDS 



25 



The elimination of calcium carbonate from these glands has 

 been known at least since 1864 when Lankester suggested that the 

 function of the glands might be associated with the formation of 

 the *'egg capsule", but even now, almost one hundred years later, 

 the specific role of the concretions in the economy of the earthworm 



CaCOj 

 spherules 



Lamellar smus 

 Lamellae 



Peripheral blood 

 sinus 



Circular 

 muscle 



Chloragogen 

 cells 



Fig. 9. Transverse section of calciferous glands of earthworm to 

 show disposition of gut epithelium blood sinuses and chloragogen 

 tissue (redrawn from Gabbay, 1958). 



is still not completely settled although recent work has made their 

 mechanisms much clearer. 



Five major theories appertaining to the function of these glands 

 are mentioned by Stephenson (1930). These are: 



(1) The absorption of oxygen. 



(2) The excretion of excess calcium (as carbonate) absorbed 

 from the gut. 



(3) The absorption of nutritious material from the gut. 



