ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 711 



carbazol impart a red violet colour to ligneous tissue. Sections are 

 immersed in an alcoholic solution of these bodies for a few minutes, 

 and having been placed in a drop of hydrochloric acid are thus 

 examined under the Microscope. The reaction begins at once and 

 increases in intensity after a short time. The stain, like that of 

 phloroglucin and indol, unfortunately is not permanent. The author 

 mentions that piridina and chinolina also give the characteristic 

 reaction. 



New Fixative Medium.* — Herren C. Born and G. Wieger have 

 found a new medium in quince-juice for fixing serial sections or for 

 staining sections on the slide. This is free from the objections 

 inherent to Giesbrecht's shellac medium, Mayer's white of egg 

 fixative, or Schallibaum's mixture of collodion and oil of cloves. 



The fixative is prepared by adding to every two volumes of quince- 

 juice one volume of pure glycerin and a little carbolic acid to 

 prevent the formation of fungi. 



The medium is applied bv spreading a thin layer upon a slide ; 

 the paraffin-imbedded section is then placed thereon, and without any 

 haste, as the glycerin prevents the adhesive layer from drying too 

 quickly. Excess of the fixative medium should be wiped off with a 

 clean cloth in order to prevent the section from moving about. The 

 slide is then dried in a warm chamber at a temperature of 30°-40° C. 

 for twenty minutes or longer. On its removal the water is found to 

 have disappeared by evaporation, and the paraffin in a smooth layer. 

 The paraffin is then dissolved out in turpentine and the slide is then 

 transferred to absolute alcohol for half an hour at least. After the 

 alcohol bath the section may be stained with any kind of dye, anilin 

 colours for choice ; it is then washed with water or spirit and cleared 

 up in the usual way. Throughout the process the adhesion remains 

 perfect and the fixative does not take up a trace of colour. Even under 

 the Microscope the fixative can scarcely ever be perceived. 



There are two points in this manipulation which it is necessary 

 to observe very strictly ; the first is that the slide must be perfectly 

 clean, otherwise the fixative may fail to adhere properly. It is recom- 

 mended to lay the slides for half an hour in cold soap and water 

 and dry them carefully with a clean cloth. The second point is that 

 in transferring from absolute alcohol to a watery staining or washing 

 fluid, the slide must always pass through at least one intermediate 

 stage of alcohol, i. e. alcohol of 50°, otherwise the violence of the 

 diffusion currents may be too strong for the fixative and cause the 

 section to become sepai-atcd from the slide. 



Chlorophyll for Staining.f — To the numerous vegetable products 

 applied to staining, Dr. N. Trinkler adds chlorophyll. He obtains it 

 from the leaves of Syringa vulgaris by extracting for twenty-four 

 hours with alcohol, evaporating the filtered extract to dryness and 

 dissolving this in water. The filtrate is a dark green with a trace of 

 brown in it. 



* Zeitschr. f. Wios. Mikr., ii. (1885) pp. 346-8. 

 t Arch. f. Mikr. Anat., xxiv. (1-885) p. 174. 



