464 NERVOUS SYSTEM— GENERAL METHODS 



on this corner by means of a small good brush and a mixture of 

 10 e.c. of Indian ink and 3 c.c. of equal parts of anhydrous ether 

 and acetone. The figures dry up instantaneously and become 

 almost engraved in the celloidin. The sections are then trans- 

 ferred to a dish of 60 to 70 per cent, alcohol. The numbers thus 

 written on the celloidin are not deleted by water and common 

 reagents, such as alcohols, up to 96 per cent., xylol, the Weigert 

 mordant, the bath used for toning and fixing Golgi-Cox specimens 

 and so on. Many sections can, therefore, be stained and treated 

 as desired at the same time and finally mounted according to the 

 progression of their numbers, provided, of course, that mounting 

 media which dissolve celloidin are not used. 



GENERAL STAINS 



990. Carmines. Ammonia-carmine is good for general views. 

 Stain very slowly in dilute solutions. Bichromate material should 

 be brought direct into the stain without passing through alcohol 

 (see § 56). 



Picro-carmine has much the same action, but gives a better 

 demonstration of non-nervous elements. 



BoLLES Lee (1913 Ed.) preferred carmalum with formol material 

 as giving a more delicate stain. He found it better than para- 

 carmine. 



The best way of staining formol material with ammonia- 

 carmine, carmalum, picro-carmine and the like, consists in making 

 frozen sections, transferring them for a few hours either to 

 Miiller's fluid, or 0-5 per cent, chromic acid as suggested by 

 ScHWALBE {Centralb. allg. Pathol., xii, 1901, p. 881). Sections 

 are then washed for a longer or shorter time according to the 

 amount of mordant one wishes to extract, proceeding afterwards 

 to stain with one of the above-mentioned carmine solutions. 



On the other hand, sections of non-imbedded material fixed 

 and hardened in one or other of the fluids mentioned in §§ 982, 

 484 may be stained not only with carmines, but also with a 

 great variety of dyes if one so desires (see ChajDter XVII:). The 

 same applies to sections of imbedded material, though the after- 

 treatment to which it has been submitted may render more or 

 less difficult the carrying out of certain general stains. One 

 should remember that in any case the results thus obtained are 

 not very instructive, and by no means comparable with those 

 attainable by the rational use of the special methods described 

 in the following chapters. 



991. Anderson's Alum Carmine {J own. Path, and Bad., xxix, 

 1926, p. 117). The following carmine solution has recently been 

 proposed for counterstaining Weigert-Pal preparations (§ 1058), 

 but can be used also for general purposes. Put 1 grm. of pure 

 carmine in a 200 c.c. flask and add 10 c.c of absolute alcohol : 



