BY DR. KLEIN. 85 



for twenty-four hours in very dilute solution of carmine; they 

 are then washed in distilled water, teased out superficially on 

 the object-glass, and mounted in glycerin. I have also found 

 it possible to demonstrate the extremely fine network of non- 

 medullated nerve fibres, with the greatest distinctness, in 

 teased preparations of sections of the gray substance of the 

 spinal cord of the calf, after maceration for two or three weeks 

 in one per cent, solution of bichromate of potash. 



Ganglion Cells of the Hemispheres. If the cortical 

 substance of the mammalian brain be macerated in iodized 

 serum, bichromate of potash, or Muller's fluid, ganglion cells 

 of more or less conical form can be isolated, from the base of 

 each of which several arborescent processes stretch inwards 

 towards the white substance, while the small end of the cone 

 terminates in a process which is simple near its origin, but 

 eventually divides into tine branches, and exhibits everywhere 

 (in iodized serum preparations) fibrillar streaking. Permanent 

 teased preparations may be obtained in the way described 

 above as applicable to the spinal cord. 



(c) Ganglion Cells of the Sympathetic System. 

 The ganglion cells of the sympathetic system occur either as 

 distinct ganglia of various size (as is seen in the digestive 

 mucous tracts, and in the genital organs), or they are ar- 

 ranged in linear series, or are scattered in greater or less 

 number amongst and between the fibres of nerves. The sym- 

 pathetic ganglia (as, for example, those of the ganglionic cord 

 or the coeliac ganglion of mammalia) are best studied as fol- 

 lows: The structure is placed in Muller's fluid or bichromate 

 of potash, and allowed to remain several days until linn 

 enough. Fine sections are then prepared, and teased in gly- 

 cerin, either at once or after staining in solution of carmine. 

 Another plan consists in steeping sections prepared from 

 frozen ganglia, in chloride of gold for ten or fifteen minutes, 

 and making from them teased preparations, which may lie 

 mounted in glycerin. Again, small fragments of fresh ganglia 

 may be steeped in one-tenth to one and a half per cent, acetic- 

 acid, and left in it from twenty-four to forty-eight hours, and 

 then employed in the same way. 



The aorta and the bulbus arteriosus of the frog afford excel- 

 lent preparations. For this purpose the vessel is ligatured at 

 the point of division, and filled with half per cent, solution of 

 chloride of gold by aid of a capillary tube. A second ligature 

 having been placed around the bulb, the part is cut out, and 

 steeped for ten minutes in the same solution. The tube is 

 then opened and exposed, two days or more, in acidulated 

 water, to the light. When of sufficiently dark color, it is 

 stuck out on a cork with pins. Thin lamella? may then be 



