Mason — Central Nervous S(/stem of Reptiles, etc. 3 



tions are stained in Beale's glycerine and water solution 

 of amnion iacal carmine, for which I often substitute the 

 borax carmine of J. W. S. Arnold, after adding to it some 

 ammonia, which rather improves the color. Transparency is 

 effected by oil of cloves, after absolute alcohol has expelled 

 the water, and the mounting is done in Canada balsam dis- 

 solved in chloroform. A short piece of copper wire hammered 

 flat at one end and bent at right angles is a good substitute for 

 the steel spoon, as it can be quickly made of any size, and its 

 outline changed by scissors when desired. 



The sections of the alligator's spinal cord, which were 

 shown with photo-micrographs at the last annual meeting of 

 the American Neurological Association, measured about 9-10 

 mm. through the brachial and crural enlargements, and were 

 made from specimens hardened by the same process as that 

 recommended by Seguin* for the human cord. 



To prepare isolate! nerve-cells, there is perhaps no better 

 method than that employed by Karabanowitsch, viz.: macera- 

 tion for forty-eight hours in a weak solution of bichromate of 

 potash (2-100) mixed, equal parts, with a (1-100) solution of 

 caustic soda and ammoniacal carmine. 



It is possible, however, to make beautiful preparations of the 

 nerve-cells of the frog, by simple agitation, with some teasing, 

 in a drop from a solution of glycerine, water and carmine. 

 Agitation in osmic acid is another common means of isolation, 

 but the preceding methods are generally to be preferred. 



The large cellular structures which form such a prominent 

 group in the inferior horns of grey matter are composed of 

 large, sharply defined nuclei, surrounded by protoplasmic 

 masses which, under the action of certain reagents, look as if 

 they were composed of fibrillin, which unite in bundles to form 

 what are called the cell processes. The nuclei seem to be 

 but slightly affected by these re-agents, but by prolonged 

 action, seem to be compressed by the surrounding mass. In 

 the cells of medium size the nuclei are rarely if ever changed 

 from the spherical form or circular appearance. These nuclei 

 which contain a distinct nucleolus, are not too numerous to be 

 counted in the frog. For example, in an unbroken series of 



'^&ri(:ffe}-^s IJandOook, p. 0-1^), 



