NEUROFIBRILS! 481 



Formula 3, A. Fix in 50 c.c. of alcohol with 10 grni. of glycerin 

 and 6 to 10 drops of ammonia. Good for retina and non- 

 medullated fibres, but especially for the buds of Held and 

 Auerbach. 



Formula 3, B. Fix in 50 c.c. of alcohol with 1-5 c.c. of a 33 per 

 cent, alcoholic solution of ethylamin. Results the same as with 

 ammoniacal alcohol. 



Formula 4. Pieces of tissue of not more than 4 mm. in thick- 

 ness are fixed for six to twelve hours in 15 per cent, formol. Wash 

 for six or more hours in running tap-water. Put for twenty- 

 four hours into 50 c.c. of alcohol with 5 drops of ammonia. Wipe 

 with blotting paper, silver for five days (or four if the stove is at 

 38° to 40° C). The rest as usual. Sharp impregnation of the 

 finer fibres of nerve-centres and of the terminal buds of peri- 

 cellular nests. Adult tissues give better results than 3'oung ones. 

 Energetic stain of the arborisations of the moss fibres of the 

 cerebellum. 



Formula 4, A. Fix in a mixture of formol and alcohol. Wash 

 out thoroughly with running tap-water, silver, and reduce as 

 usual. Fixation more rapid and better ; results similar to those 

 of 3. 



Formula 5. This is characterised by a preliminary fixation in 

 pyridin as originally suggested by Held {Arch. Anat. Physiol., 

 Anat. Abth., 1905, p. 77 ; Atiat. Anz., xxix, 1906, p. 186). He 

 used to fix tissues in pure pyridin, but Cajal finds that this is 

 likely to cause much shrinkage, and he recommends fixing small 

 pieces first for six to eight hours in a mixture of equal parts of 

 distilled water and pyridin, then for eighteen to twenty-four 

 hours in pure pyridin. Wash for several hours in running water, 

 and put for a day into 90 per cent, alcohol. Wipe, and put for 

 four to five days into 1-5 per cent, silver nitrate at 35° to 38° C, 

 and reduce as usual. Not very good for adult organs, but superior 

 to all others for the earliest phases of neurogenesis, and good for 

 regenerative processes, as well as for peripheral nerve-endings. 



Formula 6. Put for twenty-four hours into 50 c.c. of water 

 with 5 grm. of chloral hydrate, rinse, and put into 50 c.c. of 96 

 per cent, alcohol with 5 drops of ammonia (time not stated). 

 Wipe with blotting paper ; put for four to five days at 35° to 38° C. 

 into 1-5 per cent, silver nitrate, and reduce as usual. Results 

 very constant, without shrinkage. Good for the fine plexuses of 

 cerebrum, bulb and cord, the baskets of Purkinje's cells, and 

 moss fibres ; also for motor plates and for regenerating nerves. 



Denny-Brown and Hoff have used this method with success for 

 staining the " boutons terminaux " on the anterior horn cells of 

 the spinal cord. In experimental work they inject 10 per cent, 

 chloral hydrate into the aorta after washing out the vascular 

 system with saline. 



VADE-MECUM. 16 



