FOOD AND FEEDING OF OYSTERS. 



1305 



The canulas are made of glass tubing, and their tips are held for a moment in a 



Bunsen flame to produce a burr, which prevents their slipping from the ligature. 



The operation of the apparatus is as follows: The reservoir (A) is lowered 



until the water surface is about level with the stage F. The oyster is carefully 



removed from its shell and placed on the stage, its rectum is slit for a distance of 

 about one-eighth inch from the anus to facilitate the insertion of the canula, 

 which is ligated in position by means of a needle and thread. The oral canula, 

 which has a wider opening, is inserted in the mouth and ligated by means of a 



B. B. F. 190S— Pt 2—40 



