THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



VOL. IX, No. 8.] DECEMBER, 1914. [vT^To 1 



Some Methods of Embryological Technique. 



BENNET M. ALLEN. 

 Contribution from the 'Zoological Laboratory No. 210. 



THERE are two distinct lines of work to be outlined in this 

 paper. These are of especial value not only in research 

 work, but in the preparation of material for laboratory in- 

 struction. 



The writer has long felt that there should be some satis- 

 factory method of preserving fine dissections, free-hand sec- 

 lions, opaque eggs, etc., in such a manner that they could be 

 studied by reflected light under the low power of the micro- 

 scope. It has become the almost universal practice to clear an 

 object and to mount in some such substance as Canada balsam, 

 glycerine jelly, etc. The study of small opaque objects has 

 been too greatly neglected. 



Experiments were made in imbedding entire frog eggs. At 

 first glycerine jelly was used, but this was found to be alto- 

 gether unsatisfactory owing to its clearing properties. This 

 is precisely the thing that we wish to avoid. So gelatine alone 

 was employed with very satisfactory results. This is made up 

 as follows : First of all thymol was dissolved in distilled water 

 to saturation. In accomplishing this heat is employed. If the 

 solution becomes murky upon cooling, it is filtered until clear. 

 The gelatine should be prepared in the usual way — that is, it 

 should be allowed to absorb as much as possible of this thymol 

 water, and the excess water is drained off. Then it is ready 

 to be heated and used. 



Received for publication October 28, 1914. 



2 — Univ. Sci. Bull., Vol. IX, No. 8. 



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