"jG Journal of Comparative Neurology. 



then place it in a cradle made from a piece of sheet lead bent 

 in this way (^ y The sides are bent together just enough to 

 hold the specimen in place. 



The whole is then immersed in a solution of common salt, 

 glycerine and water, or any other suitable liquid of a specific 

 gravity such as will float the embryo. Then with fine for- 

 ceps, scissors, and needles piece by piece, the skin and skull are 

 removed. The pia should be removed after it has been in the 75 

 per cent, alcohol for a day or two. 



The hardening fluid must not contain glycerine, for it 

 shrinks the tissue; chromium salts make the brains too brit- 

 tle. The writer prefers plain alcohol for hardening specimens 

 to be used for gross preparations. 



Moimtiiig for Museum Specimcjts. — A convenient support 

 for small embryos is made from strips of basswood cut into suit- 

 able pieces. These are first boiled in water to which has been 

 added a little caustic potash solution, and then in water contain- 

 ing a small amount of hydrochloric acid to remove all extract- 

 ive and coloring matter. The blocks are further washed in 

 water, dried, smoothed, coated with glue and finally painted 

 with carbon drawing ink^ and dried. 



The blocks are weighted with lead. The specimen may 

 be attached by means of small pins, preferably made of silver, 

 or aluminum. 



Figuring. — The writer found great difficulty in obtaining 

 correct outlines of embryonic brains. At first an attempt to 

 photograph them was made. This method, while giving excel- 

 lent results for large specimens, proved unsatisfactory for small 

 ones. Outlines were made with the camera lucida and details 

 added free hand, the specimen being kept in a vessel of alcohol 

 all the time, whether it was to be photographed (Gage, 12) or 

 drawn with the camera lucida. The object should be well 

 lighted. 



^The use of basswood and carbon ink was suggested by Professor S. H. 

 Gage. 



