ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 109 



(4) Staining' and Injecting-. 



Staining Spirochaeta pallida.* — K. Reitmann advises fixing the 

 film in absolute alcohol for 10 minutes, and, after washing in distilled 

 water, mordanting for 5 minutes in 2 p.c. phospho-molybdic acid. 

 After washing with 70 p.c. alcohol and distilled water, the film is 

 stained with hot carbol-fuchsin. The preparation is then treated in the 

 usual way. 



G. Griemsa recommends that 1-10 drops of a 1 : 1000 solution 

 of potassium carbonate should be added to the water before it is mixed 

 with the staining solution. The stain should be allowed to act for 

 from 15-60 minutes. 



K. Herxheimer and H. Hubner stained films with a filtered aqueous 

 solution of Nile blue B. R. (1 : 1000) for from 16-24 hours. The 

 Spirochete stained dark blue. When treated with Capri blue (1 : 1000) 

 the Spirochcetce were grey. 



M. Oppenheim and O. Sachs stained films without any preliminary 

 fixation, with hot carbol-gentian-violet solution (5 p.c. carbolic acid to 

 10 p.c. alcoholic solution of gentian- violet). The films were then 

 washed and dried. The Spirochete are blue, and seem thicker than 

 when treated by other methods. 



Staining Neurofibrils.! — By use of Bielschowsky's method of re- 

 ducing the ammoniacal silver with acetic acid,J which he says is less 

 complicated and more certain than Ramon y Cajal's method, Wolff claims 

 to show that the " contiguity but not continuity " view of the nerve 

 dendrites is not supported. The dendrites are merely peculiarly 

 differentiated sensory terminals in which there is not the slightest dis- 

 continuity of neuroplasm or fibrils to be demonstrated. Successful 

 results are conditional on minute care. Method : — 



1. Fixation in 6-10 p.c. neutral formalin. Wolff has got good 

 results with weak acid reacting formalin. Previous treatment with 

 Flemming's solution, Miiller, etc., does not matter if carefully washed 

 out for several days with distilled water. 



2. Wash out thoroughly with distilled water. The pieces should not 

 be more than 2 mm. thick. Sections are best cut on the freezing 

 microtome, but may be silvered en bloc, or imbedded in paraffin and 

 the cut sections silvered. 



3. Preparatory silvering. The sections, block or paraffin cut 

 sections, placed in 2 p.c. AgN0 3 solution in dark for two or more days. 



4. Wash for few minutes. 



5. Characteristic silvering. To 10 p.c. silver nitrate is added 40 p.c. 

 caustic soda, drop by drop, until no further grey-brown precipitate 

 appears. This precipitate is then dissolved in as little ammonia as 

 possible, and diluted with 4 or 5 times its volume of distilled water (to 

 be made fresh and used with horn needles and instruments only). In 

 J-2 or more hours the yellow tone changes to a more or less deep red 

 brown. 



6. Wash in distilled water for short time to remove excess of silver. 



* Deutsche med. Wochenschr., 1905. See also Centralbl. Bakt., l*e Abt. Ref. 

 xxxvii. (1905) pp 507-8. t Biol. Centralbl., xxv. (1905) pp. 679-687. 



% Journ. Psychol, u. Neurol., 1905. 



