402 NERVOUS SYSTEM GENERAL METHODS. 



the fluid during the first days of fixation and hardening. See further 

 on this subject, 108. 



Formalin can be associated with, or followed by, alcohol ( 109) 

 or other reagents. Thus FISH (Proc. Am. Micr. Soc., xvii, 1895, 

 p. 319) recommends :- 



Water 2,000 c.c. 



Formalin . . . . . 50 ,, 



Sodium chloride .... 100 grms. 



Zinc chloride . . . . . 15 

 Brains are left in the mixture eight to ten days or longer, and then 

 transferred into a mixture of water 2,000 c.c. and formalin 50 c.c., 

 in which they may remain indefinitely if the jar is kept tightly 

 stoppered. 



PARKER and FLOYD (Anat. Anz., ix, 1896, p. 156) advise for 

 sheep's brains a mixture of 6 volumes of 95 per cent, alcohol and 

 4 volumes of 2 per cent, formol. Brains may be kept in the mixture 

 for months. 



FLATAU (Anat. Anz., xiii, 1897, p. 323) finds that brain increases 

 in weight slightly in 10 per cent, formol (spinal cord somewhat 

 more) ; whilst in 1 per cent, solution it may increase as much as 

 24 per cent. 



GEROTA (Int. Monatschr. Anat., xiii, 1896, p. 108) puts human 

 brains into a 5 or 10 per cent, solution of formol, and after twenty- 

 four hours removes the pia mater, and changes the liquid ; this is also 

 further done every five to seven days, and in one or two weeks the 

 hardening is complete. In the case of foetal brains of Canis, Felis 

 and Homo, he first injects the vascular system with a 10 to 15 per 

 cent, solution of formol in 85 per cent, alcohol, and then brings the 

 heads into the 5 to 10 per cent, watery solution ; after one or two 

 days he removes the brains from the skull and puts them back for 

 fifteen to twenty days into the formol. 



KADYI (Poln. Arch. Biol. Med. Wiss., i, 1901, p. 80) takes 5 parts 

 of formol, 100 of water, and 2 of bicarbonate of soda, for four to ten 

 days. 



HERDLICKA (Proc. U. S. Nat. Mus., xxx, 1906, p. 304) takes 3 parts 

 of formol, 25 to 45 of water, and 72 to 52 of 95 per cent, alcohol. 



STRECKER fixes small pieces for twenty-four to forty-eight hours in 

 equal parts of 10 or 20 per cent, formol and Ehrlich-Biondi triacid 

 mixtures, and imbeds in paraffin, thus getting a stain at the same 

 time as a fixation. Similarly with toluidine blue fixing it with 

 ammonium molybdate. See Ztschr. wiss. Mikr., xxviii, 1911, 

 p. 17, and the literature discussed therein. 



