500 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Staining the Grey Matter of Spinal Cord after Mordanting with 

 Metallic Salts.* — Kadyi states that after hardening in formalin and 

 mordanting with the acetates of uranium, lead or copper, staining with 

 carmin is very successful. Four variants of the method are given. In 

 the first the grey matter only is stained, the white remaining unstained. 

 After removal from the formalin the pieces are washed and then trans- 

 ferred to a mixture of uranium acetate 1 p.c. and acetic acid 1 p.c, 

 wherein they remain for a few hours to a few days according to their 

 size. The sections are stained in 0*2-0 - 5 p.c. solution of carminate 

 of soda or in ammoniacal carmin. The second procedure imparts stain- 

 ing to the neuroglia. The sections after having been mordanted in 

 uranium acetate are transferred to a solution of potassium nitrate. By 

 the third method a deep staining of the white matter is obtained, the 

 grey remaining almost colourless. In this case the sections are treated 

 with potassium nitrate before they are mordanted. The fourth imparts 

 a stain to the axis-cylinders only. For this the pieces of spinal cord 

 are hardened in neutral or alkaline formalin solution (distilled water 

 100 ; bicarbonate of soda 2 ; formalin 5). The 1 p.c. copper acetate 

 mordant must not contain any free acetic acid. After the sections have 

 been mordanted they are washed in 2 p.c. potassium nitrate, and after 

 having been stained are differentiated in a solution composed of dis- 

 tilled water 100 parts; carminate of soda 1 part; potassium nitrate 

 2 parts. When sufficiently decolorised, the sections are washed in 

 2 p.c. potassium nitrate until the pigment is no longer given off, after 

 which they are treated with absolute alcohol and chloroform and then 

 mounted in balsam. 



Staining the Medullary Sheath of Nerve-Fibres.f — W. H. Wynn 

 fixes and hardens the material in 5 p.c. formalin, and sections it on a 

 freezing microtome, using no gum. The sections are mordanted for 

 24 hours in the cold in 2 p.c. ammonium molybdate, iron-alum or 

 uranium acetate or they may be incubated at 40° C. for a few hours. 

 After washing, they are stained for some hours in acid hematoxylin, 

 or for two hours in the incubator. They are again washed and after- 

 wards differentiated by Pal's method : the sections are first placed in 

 potassium permanganate solution and next in Pal's solution, the baths 

 being alternated until the required differentiation is obtained. They 

 are again washed, after which they are mopped up and then transferred 

 to absolute alcohol. After draining off the alcohol they are passed 

 through chloroform and xylol successively and mounted in balsam. 



Instead of Pal's solution, Bolton's method may be used for dif- 

 ferentiating. This consists in immersing the sections in a moderately 

 dilute solution of ammonia by which the unattached lake is quickly 

 dissolved out, leaving differentiation complete. 



Staining the Neuro-fibrils in the Ganglion-cells of the Cerebral 

 Cortex.! — S. Paton immerses the material for 24 hours in a saturated 

 solution of sublimate containing 5 p.c. acetic acid. It is then trans- 

 ferred to 95 p.c. alcohol which should be changed at least once a day 



* Neurol. Centralbl., xx. (1901) pp. 6S7-8. 



t Journ. Anat. Physiol., xiv. (1900) pp. 3S1-97 (2 pis.). 



X Journ. Exp. Med., v. (1900-1901) pp. 21-5 (1 pi.). 



