392 CHAPTER XXXTI. 



They remain in this for twenty-four hours. They are then 

 washed, hardened in. alcohol, imbedded in celloidin or paraffin, 

 and sections mounted in damar. 



Tellyesnicky {Verh. Anat. Ges., 1904, p. 183; advises toning the 

 sections for five to thirty minntea in 150 c.c. of water with 4 c.o. of 

 1 per cent, gold chloride. This is good for weak impregnations, hut 

 not desirahle for strong ones which show good contrast. 



Sections from the outer layers are too dark for studj^, 

 those from the innermost too pale (if the specimens are 

 large ones), whilst those from intermediate layers are fit for 

 study. The over-stain of the outer layers can be diminished 

 by diluting the sihi^er bath with 1 volume of water for the 

 last twelve hours. 



This method has the defect of giving an imperfect fixation 

 and impregnating almost exclusively cell-bodies and dendrites. 

 It is not good for the large cells of adults, but excellent for 

 small and medium cells of newborn or very young subjects, 

 and for very early embryos in general. 



Formula la A. — As last, but with nitrate of silver of 3 to 

 6 per cent. 



DoGiEL [Anat. Ariz., xxv, 1904, p. 558) finds this method 

 gives results not attainable by other means in the study of 

 the corpuscles of Geandey (stoving for four to six days). 

 Similarly Kolmer {ibid., xxvi, 1905, p. 560) with epiderm of 

 Lumbricus, etc. ; and other authors for the ganglionic cord 

 of Hirudinea. 



Formula la B. — As before, but nitrate bath of only 0'75 

 per cent., and very small pieces of tissue, preferably embryos 

 and newborn subjects. Poor fixation, much shrinkage, but 

 vigorous stain of neurofibrils, of nucleolar granules, and of 

 the intra-nuclear rodlet of Roncoeoni. 



Formula la C. — As before, but silvering in nitrate of 2 per 

 cent, with one fourth of absohde alcohol or acetone added. 

 Better fixation than pure nitrate. Gives results very similar 

 to those of la with dog, cat and rabbit, and better results 

 with human cerebrum and cerebellum. 



Formula 2a. — Fixation for 24 hours in alcohol of 96 per 

 cent. Tissues not washed, but mopped with blotting- 

 paper, and put into nitrate of silver of 1-5 per cent, for 

 seven diiys at .35° C., or six days at 40° C. The rest as 



