Vol. xir 



■895 . 



Correspondence. 



197 



In operating on fresh eggs of size of common hen or less, use a drill 

 not larger than .04 in. diameter; with small eggs .02 in. drill answers the 

 purpose. Insert the point of tube /in the egg after turning on the water, 

 and the contents of the egg pass rapidly over into the flask, provided the 

 tube be not of too small calibre. In practice it is well to have a number 

 of these tubes of different diameters. 



Make connection between aspirator and water main at A. Provide means 

 for carrying away waste water. 



The water in passing through aspirator rarifies the air in K. 



A, B, D, Chapman aspirator. 



E, H, Pieces of rubber tubing. 



G, F, Pieces of bent glass tubing. 



J, Rubber stopper, doubly perforated. 



K, Conical filtering flask capable of withstanding atmospheric pressure. 



I, Glass tube drawn to small calibre at one end. 



The tubing used to make tube /should have very thin walls, that the 

 internal diameter of the attenuated point may be relatively large. It 

 would appear that there is great danger of collapse if the suction tube 

 nearly fills the aperture in the shell of the egg, but with fresh eggs I have 

 never known it to occur. With eggs in an advanced state of incubation, 

 however, care must be taken to allow air to enter freely around the tube. 



I have found little difficulty in removing fully formed embryos from 

 eggs as large as the Robin's, using an .08 in. drill and a suction tube of 



