376 NERVES. 



713. There remain to be mentioned some variations in the 

 details of the process, chiefly connected with the strengths of 

 the solutions to be used and the duration of the impregnation- 

 baths. 



MONDINO (Arch, per le Sci. Med., viii, p. 45 ; Zeit. f. wiss. 

 Mik., 1885, p. 547) recommends that the preparations be left 

 in the bichromate mixture longer than directed by Golgi 

 viz. from one to eight days ; and also that they be left for 

 over twenty-four hours in the silver-bath. 



For some minutiae concerning the application of the bichromate and silver 

 method to cerebro-spinal nerves, see PETEONE, in Internat. Monatschr. f. 

 Anat., v, 1, 1888, or Zeit.f. wiss. Mik., v, 2, 1888, p. 238. 



714. RAMON Y CAJAL, who has done a great deal of im- 

 portant work by Golgi's method, has always used the rapid 

 process. In Zeit. f. wiss. Mik., vii, 3, 1890, p. 332, he gives 

 it as follows : Fresh muscle of insects put into a mixture of 

 20 parts 3 per cent, bichromate solution and 5 parts 1 per 

 cent, osmium solution for twelve to twenty-four hours, then 

 into 0'75 per cent, nitrate of silver for one day, then alcohol 

 of 40 degrees (presumably Baume, i. e. about 90 per cent.), 

 then clove oil followed by resinified turpentine and (if I under- 

 stand rightly) balsam. For the times and strengths used by 

 him in his researches on the cerebral cortex of mammals, see 

 his paper in La Cellule, vii, 1891, p. 125, or Zeit. f. wiss. Mik., 

 ix, 2, 1892, p. 239 ; also Journ. Roy. Hie. Soc., 1892, p. 154. 

 He generally hardened for from five to eight days at a 

 temperature of about 25 C., and found it useful to adopt 

 Sehrwald's gelatin process (supra, last section) for avoidance 

 of peripheral precipitates. He prefers not to adopt Greppm's 

 treatment with hydrobromic acid, nor Obregia's treatment 

 with gold chloride, finding that although they serve to 

 render the preparations permanent, they obscure the finer 

 relations of fibres. 



For embryos of the fowl he employs the same process ; 

 see his paper in Anat. Anz., v, 1890, p. 85, or Zeit. f. wiss. 

 Mik., vii, 2, 1890, p. 235. 



715. In a paper on the structure and relations of the sympa- 

 thetic ganglia (which I have not seen, and quote from Zeit. f. 

 wiss. Mik., 1. c.) RAMON Y CAJAL describes a process of "in- 

 tensive" or "double" impregnation. After hardening for 



