400 PREPARING THE SPINAL CORD. 



aqua solution), followed by picro-carmine, as I find the combina- 

 tion more effectual than any single stain in bringing out all the 

 structures in the section (grey and white matter). Kernschwarz, 

 diluted to one-third the original strength (five to ten minutes) is 

 an excellent stain for the axis cylinders ; it stains nerve-cells rather 

 too uniformly. By using subsequently the Biondi-Ehrlich stain 

 (ten minutes) they are brought out better. An entirely satisfactory 

 staining of the grey matter is yet to be obtained. By means of 

 Leoffler's alkaline methylene blue (aqua solution, dilute before use 

 with an equal volume of water), the nerve-cells and the connec- 

 tive tissue throughout the section can be stained, but the nerve- 

 tubes are poorly shown. Excess of dye is removed by the piridin 

 which follows. Picro-carmine (half-an-hour) stains all the struc- 

 tures present ; but I have hitherto got the most satisfactory results 

 by staining first in aniUn-blue-black of the strength given, for 

 twenty minutes, and subsequently in picro-carmine for fifteen to 

 twenty "minutes. The staining of the grey matter will, I hope, be 

 presently improved upon. My immediate object is more espe- 

 cially to bring to notice the fact that by means of piridin, sections 

 of the fresh cord can be fixed and preserved unwrinkled, each 

 nerve-tube being well defined. 



Sections prepared and "mounted in the manner described show 

 scarcely any diminution in size when compared with the original 

 cord. I'he rapidity of the method is noteworthy, for by it the 

 cord can be removed, cut, stained, and mounted in the course of 

 a day ; indeed, it is probable that from two to four hours would 

 suffice. 



In conclusion, I may state that I have hitherto practised with 

 the cord of the cow, cat, and rabbit respectively, in each case suc- 

 cessfully, with the reservation regarding the grey matter alluded to. 

 The longest period which has elapsed between the death of the 

 animal and the time of cutting sections (after which the elements 

 were thoroughly fixed) is an hour and a-half (cow's cord). I have 

 not yet cut any later than this. Judging from certain specimens, 

 in which nerve-roots appear outside the cord in transverse section, 

 I am disposed to think that the same method may be advantage- 

 ously employed in peri])heral nerves. 



