GIACOMINI'S "DRY" PROCESS. 409 



use (which will always eventually happen), it may be reprepared by putting 

 it back into the alcohol, and thence again into the xylol. 



BEVAN LEWIS (The Human Brain, p. 122) proceeds as follows : A sec- 

 tion is placed, saturated with spirit, on a slide. When the spirit has nearly 

 all evaporated, a drop of oil of anise is allowed Ito flow over the section (not 

 to float it up), and the clearing is watched on the stage of the microscope ; 

 then, just when the desired image is arrived at, a drop of balsam is allowed 

 to run over the section, and a cover put on. 



Instead of oil of anise, Lewis has frequently employed glycerin followed 

 by mounting in glycerin jelly, with the same results. 



BYBOJI BEAMWELL (Edinb. Med. Journ., Oct., 1886) also recommends 

 the process. He uses clove oil. 



780. GIACOMINI'S "Dry" Process for Preserving Brains (Arch, per 

 le Scienze Mediche, 1878, p. 11). Although this is in intention a macro- 

 scopic method, it appears worth while, both on account of its thorough success 

 and on account of its suggestiveness, to give a description of it here. 



The object is to make " dry " preparations of the encephalon ; by which 

 is meant preparations that can be permanently preserved in the air. The 

 methods hitherto employed were not successful because they consisted in 

 making preparations that were "dry" in the literal sense of the word that 

 is, deprived of their natural water; and since brain-substance contains 88 per 

 cent, of water, such preparations could not of course be obtained without so 

 great an amount of shrinkage as to most seriously diminish the scientific 

 value of the result. The principle of Griaconrini's method is, on the contrary, 

 to retain the natural water of the tissues, or an equivalent for it, by means 

 of impregnation with a hygroscopic substance, glycerin. 



The process consists of two divisions : 1, hardening ; 2, impregnation 

 with glycerin. 



1. For hardening may be used zinc chloride, bichromate of potash, 

 chromic acid, nitric acid, or alcohol. 



Chloride of zinc gives the best results. Perfectly fresh brain is put into 

 a saturated aqueous solution of the salt (if there be reason to fear that the 

 tissues are somewhat softened through having been left too long after the 

 death of the subject, it is well first to inject 600 grms. of the solution 

 through the internal carotid arteries). After forty-eight hours' immersion 

 (during which time the floating brain must be turned over three or four 

 times, so that all parts of it may duly come into contact with the liquid) the 

 surface of the brain will have attained a consistency that will allow of the 

 removal of the arachnoid and pia mater. The meninges having been removed, 

 the encephalon is put back into the solution for two or three days more, 

 during which time it will be seen that, increasing in specific gravity, it tends 

 towards the bottom of the vessel containing it. When this is seen to happen 

 it must be removed into commercial alcohol, as if allowed to remain longer 

 in the chloride of zinc solution it would take up too much water. 



In the alcohol it may remain for an indefinite time, or it may be removed 

 if desired after ten or twelve days. (During the alcohol-bath it must be 

 frequently turned over in order that no malformation may arise from con- 

 tinuance of pressure on the same part.) 



