NEUROLOGICAL METHODS. 389 



DUVAL'S method of collodioiiising the sections. The cut sur- 

 face of the tissue is dried by blowing on it, and is covered 

 with a thin layer of collodion laid on. it with a brush. As 

 soon as this layer has somewhat dried, which happens very 

 rapidly, a section is cut and the cut surface is collodioiiised 

 as before, and so on for each section. This process gives 

 very good results, and may be advantageously employed even 

 with material that has been successfully imbedded, as it 

 gives a better consistency to the tissue, and enables thinner 

 sections to be obtained (VAN GEHDCHTEN, in lift.). 



STRASSER (Zeit.f. u-iss. Hik., ix, 1892, p. 8) obtains paraffin 

 sections of 10 cm. breadth by 15 crn. length. He cuts out 

 from hardened material slices of from 1 to 2 cm. in thickness, 

 de-alcoholises them with xylol-carbolic acid mixture, 161, 

 allows this to evaporate, and brings them first into melted 

 yellow vaselin, and lastly either into a mixture of vaselin and 

 paraffin of 42 melting point, or into pure paraffin. 



He also imbeds the slices in celloidiu, and clears them 

 before cutting with a mixture of xylol-carbolic acid and 80 

 per cent, alcohol in equal parts. 



FEIST (Zeit. f. wiss. Mik., viii, 4, 1892) gives a useful hint for marking 

 the right and left sides of spinal cord. He imbeds with each segment of 

 the cord a small cylinder (of about 1 square millimetre in section) of hard- 

 ened liver, stuck vertically in the imbedding mass (either celloidin or 

 paraffin) against the side of the cord that it is desired to mark. 



For further details concerning imbedding and cutting, see 

 last edition. 



CYTOLOGICAL METHODS. 

 Nerve cells. 



695. NISSL'S Methylen-blue Method (Neurol. Centralb., 1S94, 

 p. 508). Fresh material is hardened in 96 per cent, alcohol, 

 and sectioned without imbedding. The sections are brought 

 into a watch glass with the following stain : 



Methylen blue (Methyleiiblau pat.) . 3'75 parts. 

 Venice soap . . . . 1'75 



Distilled water . . . lOOO'O 



The watch glass is warmed over a flame to about 65 to 70 C., 

 till bubbles are given off which burst at the surface of the 



