Chap. I. CALCIFEROUS GLANDS. 49 



during the winter ; and I have seen some 

 instances of this fact, and others in which 

 either the anterior or posterior glands were 

 at this season so shrunk and empty, that 

 they could be distinguished only with much 

 difficulty. 



With respect to the function of the calci- 

 ferous glands, it is probable that they pri- 

 marily serve as organs of excretion, and 

 secondarily as an aid to digestion. Worms 

 consume many fallen leaves ; and it is known 

 that lime goes on accumulating in leaves until 

 they drop off the parent-plant, instead of 

 being re-absorbed into the stem or roots, like 

 various other organic and inorganic sub- 

 stances.* The ashes of a leaf of an acacia 

 have been known to contain as much as 

 72 per cent, of lime. Worms therefore would 

 be liable to become charged with this earth, 

 unless there were some special means for its 

 excretion ; and the calciferous glands are 

 well adapted for this purpose. The worms 

 which live in mould close over the chalk, 

 often have their intestines filled with this 

 substance, and their castings are almost white. 



* De Vries, * Landwirth. Jahrbucher,* 1881, p. 77. 



