CHAP. I. CALCIFEKOUS GLANDS. 47 



tion of carbonate of lime, as much as 1^ mm. 

 in diameter. When a gland includes only 

 .a few very small concretions, or, as sometimes 

 happens, none at all, it is easily overlooked. 

 The large concretions are round or oval, and 

 exteriorly almost smooth. One was found 

 which filled up not only the whole gland, as 

 is often the case, but its neck ; so that it 

 resembled an olive-oil flask in shape. These 

 concretions when broken are seen to be 

 more or less crystalline in structure. How 

 they escape from the gland is a marvel ; but 

 that they do escape is certain, for they are 

 often found in the gizzard, intestines, and 

 in the castings of worms, both with those 

 kept in confinement and those in a state of 

 nature. 



Claparede says very little about the 

 structure of the two anterior glands, and he 

 supposes that the calcareous matter of which 

 the concretions are formed is derived from 

 the four posterior glands. But if an anterior 

 gland which contains only small concretions 

 is placed in acetic acid and afterwards 

 dissected, or if sections are made of such 

 a gland without being treated with acid, 



