[ 293 ] 



flDicroacopical Zccbniqwc. 



Double-Staining Spinal Cord, etc.— Albertrand, of Vienna, 

 describes a new method of staining the spinal cord and its mem- 

 branes with a double colour, consisting of chloride of iron and 

 tannin. The section is first submitted to a 50 per cent, solution 

 of the sesquichloride of iron for ten or fifteen minutes, then 

 washed in water, and next submitted for one or two hours to a 

 twenty per cent, solution of tannin, after again washing. The 

 colour is differentiated by Pal's solution. These give sharp, 

 clearly defined images of the nerve fibres in the grey substance, 

 both of the spinal cord and the brain, which is a great improve- 

 ment on Weigert's haematoxyHn. The alcoholic preparations can 

 be clearly brought out with this method, which is difficult to 

 obtain with Weigert's solution The colouring of alcoholic pre- 

 parations affect the remnant of the sheath alone, as the spirit 

 extracts the myelin, leaving only the framework of the sheath to 

 be coloured. How this was acted on he would not venture to 

 explain, but believed the changes to be similar to that in Kiihn 

 Ewald's Netiro-Keratingeriist. With the differentiating colour the 

 axis-cyhnder stands out sharply defined as a dark line on a colour- 

 less ground. — The Medical Press. 



The Proper Angle for the Razor in Paraffin Sectioning.— 

 In the discussion between Dr. M. Heidenhain and Dr. B. Rawitz, 

 relative to section cutting and the staining of microscopic prepara- 

 tions, the latter person* upholds the advice that he gives, in 

 his Leitfaden, and adduces experimental proof to show that the 

 microtome knife should be placed at an acute angle to the stroke 

 rather than at a right angle. When placed at the latter angle, the 

 sections, according to their thickness, are always more or less 

 crowded together, thus distorting the finer structures of the tissue 

 cut. The experimental proof consists of the measurement of 

 sections cut with the knife at a right angle, and with it at an angle 

 of 45*^. The sections were from a block of paraffin measuring 

 20J by 11^ mm., and had a thickness of 15/*, lo/t, and 5At. With 



* (( 



Bemerkungen iiber Mikrotomaschneiden und iiber das Foben Mikros- 

 kopischer Praparate."— ^«a/, Anz., xiii., pp. 65—80. 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. VII. v 



