484 NEUROFIBRILS 



the incubator. After a quick wash they are reduced for five to eight 

 hours in Amidol-Hauff 0-5 gr., sodium sulphite cryst. 10 grm., distilled 

 water 100 c.c, and lastly passed into glycerin. Preparations are made 

 by teasing, the thinner ones being toned and counterstained as usual. 

 For mounting he prefers Apathy's syrup. 



Ranson {Anat. Anz., xlvi, 1914, p. 522) has the following for the 

 demonstration of non-medullated nerve-fibres in cranial and peripheral 

 nerves : Fix in absolute alcohol containing 1 per cent, of strong 

 ammonia for forty-eight hours ; rinse in distilled water, put in pyridine 

 for twenty-four hours, place in 2 per cent, silver nitrate at 35° C. in the 

 dark for three days, rinse in water, and place for one day in a 4 per cent, 

 solution of pyrogallic acid in 5 per cent, formalin. Hewer (Journ. 

 Anat., Ixvii, 1933, p. 350) uses Ranson's technique on material fixed in 

 7 per cent, formalin and has had satisfactory results by reducing in 4 

 per cent, pyrogallol without the addition of formalin. 



As suggested by Huber and Guild (Anat. Rec, vii, 1913, p. 253) the 

 results can be improved by a preliminary injection of 95 per cent, 

 alcohol, containing 1 per cent, of ammonia, through the arteries till 

 tissues are thoroughly saturated, after which they are dissected out and 

 placed in a similar ammoniated alcohol solution for from two to three 

 days. Hiiber and Guild have found this method of use for the study of 

 cranial nerves of small animals and embryos, since the entire heads can, 

 after fixation, be decalcified by means of 7 per cent, nitric acid, brought 

 through 80, 90, and 95 per cent, alcohols, each containing 1 per cent, of 

 ammonia, and finally treated as above. 



C. RECENT METHODS 



1014. Ramon y Cajal's (1) Method for Sections of Cortex 

 Cerebelli {Trab. Lab. Invest. Biol., xix, 1921, p. 71). The idea 

 of this method appears to have been suggested in part by 

 Liesegang's modification {op. cit., p. 1057) in part by the prin- 

 ciple underlying the Bielschowsky method for sections. Frozen 

 sections from formalin material are collected in water to w^hich 

 a few drops of formalin are added. Before carrying out the 

 staining they are washed in two changes of distilled water and 

 transferred into a bath consisting of 10 c.c. of 2 per cent, silver 

 nitrate and 5 to 8 drops of pyridin. They are either left therein 

 in the dark from twelve to forty-eight hours or {Trab. Lab. Invest. 

 Biol., xxiii, 1925 — 6, pp. 162 — 4) warmed over a flame for some 

 minutes. When they have assumed a light brown colour they 

 are placed for half a minute in 96 per cent, alcohol to which 2 

 to 3 drops of 2 per cent, silver nitrate may be added if an intense 

 stain is desired. Without washing, the sections are transferred 

 into the reducing fluid, consisting of 30 c.c. of formalin, 70 c.c. of 

 distilled water and 0-20 to 0-30 grm. of hydroquinone. The 

 reduction is complete after one minute, when the sections can 

 be washed in distilled water, dehydrated, cleared and mounted 

 in balsam. Toning is not, as a rule, necessary ; but it can be 

 easily carried out by means of a 1 : 300 solution of gold chloride 

 followed by fixation in dilute sodium hyposulphite or 1 per cent, 

 thiosinamine. If the background is very dark the sections can 



