Journal of Applied Microscopy 



and 



Laboratory Methods 



Volume VI. NOVEMBER, 1903. Number 11. 



A Method of Removing Chick Embryos. 



One of the chief difificulties encountered in the removal and fixation of chick 

 embryos is the wrinkling, curling up, and folding, which occur when the fixative 

 is applied. 



Foster and Balfour (Elements of Embryology, 1896 p. 44^2) direct to float 

 the embryo on a glass slide, allow the edges to dry fast and then immerse slide 

 and chick in the fixative. Lee's Vade-Mecum recommends that the chick be 

 spread out on the convex surface of a watch-crystal and then immersed. Both 

 of these methods 'are cumbrous, and it is often difficult to remove the embryo 

 from the slide after fixative without injury. In some laboratories the embryo is 

 pinned out on wax or cork with animal spines and then immersed in the fixative. 

 This often results in distortion and tearing. 



I have used the method hereafter described for several years and find it gives 

 such uniformly good results that it seems worth while describing for the benefit 

 of those who are not familiar with it. This method is used in several labora- 

 tories and the author makes no claim of originality for it. 



Holding the egg, lying on its side, in one hand, crack the shell around some- 

 what above the equator. Beginning at the larger end of the egg, with blunt 

 scissors cut through the shell and shell membranes completely around the egg, 

 or break the shell and membranes around this line with fine forceps. Care must 

 be taken not to push the point of scissors or forceps too far through the shell or 

 the vitelline membrane will be punctured. The cutting of the shell is attended 

 with less risk to the embryo if the side of the egg which lies uppermost while in 

 the incubator is kept uppermost during the operation, and if a part of the albumen 

 is allowed to run out at the opening made in the larger end of the egg before 

 proceeding with the cutting. 



After the shell has been cut completely around, the upper cap of the shell 

 may be removed and part of the albumen poured off, leaving the yolk in the 

 larger part of the shell. 



While this method is attended with more risk than the method by which the 

 shell is removed in small pieces from the shell membranes, and then the latter is 

 removed in strips with forceps, yet the saving in time more than compensates for 

 the slight loss of embryos. 



The part of the shell containing the yolk is now immersed in a vessel of 



(2589) 



