XHRVOUS SYSTEM — CYTOLOGICAL METHODS. 397 



6a. For buds of Held and Auerbach, and for fine plexuses, 

 4a, 3a A, or 5a. 



(8) Ganglia of Invertebrates. — For the medicinal leecli 

 (not for other leeches), la with 3 to 6 per cent, of nitrate. 

 For Hsemopis, Aulostomuvi, FontobdeUa and Glossiphonia, 2a 

 or, better 3a, with not more than two to five drops of 

 ammonia, and silver of 3 per cent., three to three and a half 

 days. 



For further details see Sanchez in Trab. Lab. Invest. 

 Biol. Madrid, vii, 1909, p. 31, or Zeit. wiss. Mik., xxvii, 

 1910, p. 392. 



Lunibricits is generally refractory to Ramon's methods. 

 BouLE {Le Nevraxe, x, 1909, p. 15) obtains good impregna- 

 tions by acidifying the fixatives. He takes (A) formol of 25 

 per cent, with 5 per cent, of acetic acid, or (B) the same 

 with 0"5 per cent, of ammonia added, or (0) 100 c.c. alcohol, 

 25 c.c. formol, 5 c.c. acetic acid and 0'5 c.c. ammonia. These 

 results are confirmed by KowALSKr, La Cellule, xxv, 1909, p. 

 292, who also gets impregnations by simply starving worms 

 for several days, or exposing them to cold (—5° C.) for a 

 quarter of an hour. 



(9) Regenerating nerve tissue. — For nerves operated a 

 month or more previously, 2a or 3a with not more than three 

 drops of ammonia will stain equally the old and the new 

 fibres. For nerves operated not more than two to ten days 

 previously, 3a with 4 to 6 drops of ammonia, 5a with pyridin 

 and 4a, also sometimes 6a. For regenerations in cord, 

 cerebrum and cerebellum, 3a with three drops of ammonia, or 

 5a with pyridin, or pure alcohol. 



769. Variants of Ramon's Methods. — Bbsta {Biv. Path. New. 

 Ment., Firenze, xv, 1910, p. 333) fixes for 48 hours in alcohol with 5 per 

 cent, nitric acid, neutralises in alcoLol with ammonia, and silvers and 

 rediices as Ramon. 



Kato {Folia NeurobiuL, ii, 1908, No. 3 ; Zeit. wiss. Mih:, xxvi, 1909, 

 p. 281) fixes in formol of 10 to 15 per cent., and silvers for one to five 

 days at 35° C. in 5 per cent, argentamin to which has been added 

 nitrate of silver of 3 per cent, in excess, and reduces in 10 per cent, 

 formol with 1 per cent, of hydroquinon. 



Ptisatebi {Arch. Path. Anat., 195 Bd., 1909, p. 547) fixes for three to 

 six days at 35° to 38° 0. in a mixture of 45 c.c. of tachiol {10 per cent, 

 solution of fluoride of silver) with 155 of water, rinses and reduces for 

 24 hours in formol of 5 to 10 per cent, with 1 to 2 per cent, of hydro- 

 quinon. He tones the paraffin sections in 10 c.c. of water with 2 



