NOTES AND MEMORANDA. 161 



centrated ammoniacal solution of carmine. In this it becomes 

 almost instantaneously coloured red, and the most beautiful 

 colour is obtained when the red still shows a sliglit shade of 

 yellow. Tlie section is then washed and prepared in the 

 usual way for putting up in Canada balsam or Dammar var- 

 nish. The axis cylinder is, in preparations made by this 

 method, bright red, and the medullary nervous matter yellow ; 

 if allowed to remain too long in the carmine solution, the 

 medullary substance also becomes red, Avhicli, however, does 

 not interfere with the distinctness of the preparation. If the 

 sections remain too long in the palladium solution, they gra- 

 dually become darker, and are spoilt. 



Moiybdate of Ammoniuni.— This reagent is also recom- 

 mended by Merkel in Henle's ' Anatomy,' for tinting pre- 

 parations of the nervous system. The solution is thus pre- 

 pared : — One part by measure of a quite concentrated solu- 

 tion of moiybdate of ammonium is diluted with one or two 

 parts of water ; to this solution is added as much iron filings 

 as will lie upon the point of a knife, and commercial hydro- 

 chloric acid is slowly added, drop by drop, with continual 

 agitation, till a deep blue, almost black, colour is produced. 

 The white flocculent precipitate first formed on addition of 

 acid is of no consequence, and readily redissolves on agita- 

 tion. If, however, the solution becomes brown instead of 

 blue, as sometimes happens, it is useless. When the solu- 

 tion has acquired the desired colour, it is allowed to stand 

 for ten minutes, and then filtered. A blue solution is thus 

 obtained, which may be, if necessary, diluted with water. 

 Sections of the spinal cord, or medulla oblongata (it is less 

 suitable for brain), laid in it are stained blue, according to 

 the degree of concentration of the solution, in six to fifteen 

 hours. The coloration is very thorough, and apjiarently 

 homogeneous, though in good preparations the axis cylinder 

 shows very clearly. The preparations may be put up in the 

 usual way in Canada balsam, being first dehydrated by 

 alcohol, and rendered transparent by oil of cloves. 



(Esophagus of Sauropsida — At a late meeting of the Zoolo- 

 gical Society a paper was read on the oesophagus of the 

 hornbill, a bird which, though known to eject food or other 

 matters voluntarily by this tube, now proves to be devoid of 

 an oesophageal sheath of transversely striped muscle ; and 

 this fact agrees with the former observations of the author, 

 Mr. Gulliver, that such sheath is wanting in reptiles and 

 birds, while fishes and mammals are regularly provided 

 therewith. In this highest class, the difference of the extent 

 of the striped muscle on the oesophagus of different orders is 



