Kansas Mmm Science Bulletin. 



Vol. IV, No. 18. SEPTEMBER, 1908. | vJL°xVno 11' 



SOME LABORATORY METHODS IN EMBRYOLOGY, II, 



INCLUDING A DESCRIPTION OF A SIMPLE PARAFFIN-BATH 

 AND A NEW STYLE OF SECTION-KNIFE. 



BY R. G. HOSKINS. 



(Contribution from the Zoological Laboratory, No. 185.) 



One figure. 



IN a previous paper* was given a summary of the technical 

 methods used in dealing with embryological material in 

 the laboratories of the University of Kansas. The sub- 

 ject of holoblastic cleavage material, however, was not treated 

 in detail. This paper is largely an attempt to remedy that defi- 

 ciency. The methods are given in some detail, as the difficul- 

 ties of handling this sort of material lie mainly in the minutiae. 

 No attempt to assign specific credit is made; the methods are 

 the result partly of suggestions from the literature on tech- 

 nique, partly of suggestions by Doctor McClung and partly 

 the outcome of experimentation by the writer. 



For illustrating holoblastic cleavages, frog and salamander 

 eggs are used. For studying the whole eggs the latter are 

 more satisfactory on account of their having less pigment; 

 for sectioning they are about equally good. 



Various methods of making whole mounts were tried — using 

 both glycerin- jelly and balsam. It was found that, on ac- 

 count of the difficulties of sealing glycerin- jelly mounts, bal- 

 sam is decidedly the more satisfactory. The eggs are first fixed 

 in four per cent, formalin, which hardens them slightly, but 

 leaves the gelatinous matrix that surrounds them unchanged. 

 The removal of this envelope follows next. This is rather a 

 baffling or decidedly an easy matter, depending upon the 

 method used. The best way is simply to roll the eggs over 



* "Some Laboratory Methods in Embryology," Kan. Univ. Sci. Bull. IV, 4. 



(371) 



