ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1061 



Kbtsinski, S. — Beitrage zur histologischen Technik. 1. See Imbedding. 2. Indigo- 

 cannin als Tinctionsmittel. 3. Alauncarmin. (Contributions to histological tech- 

 nique. 2. Indigo carmine as a staining agent. 3. Alum carmine.) 



Virchow's Arch. f. path. Anat. u. Hist,, CVIII. (1887) pp. 217-9. 

 Wbigert, C. — tiber eine neue Methode zur Farbxing von Fibrin und von Micro- 

 organismen. (On a new method of staining fibrin and micro-organisms.) 



5 pp., 8vo, Berlin, 1887. 



(5) Mounting-, including: Slides, Preservative Fluids, &c. 



Mounting Sections without Cover-glasses.* — Dr. C. Weigert recently 

 showed that celloidin sections could be cleared up with carbol xylol, and as 

 many of these sections were intended to be mounted under the same cover- 

 glass it was found in practice to be somewhat expensive to provide cover- 

 glasses of sufficient size. He resolved to follow in Golgi's footsteps, and 

 do without the cover-glass, but as the Italian method has several in- 

 conveniences attached to it he adopted the photographic negative varnish 

 as the substitute for dammar. 



After the sections have been cleared up with carbol xylol, the excess 

 of fluid is removed in the usual way with blotting-paper, and a thin layer of 

 the negative varnish is poured on. This dries very quickly. The drying 

 may be accelerated by gently warming the slide, and this must always be 

 done if the layer appears cloudy. When the first layer is dry, another coat 

 is laid on, and so on until the surface remains quite smooth. Three coats 

 are usually sufficient. When finished, the surface may, if necessary, be 

 wiped or washed with water ; high powers and even oil-immersion lenses 

 may be used in the examination. In the latter case, a small drop of water 

 must be placed on the surface, and upon this a cover-glass. This method 

 cannot be used for sections stained with the anilin dyes as the carbol xylol 

 destroys them. 



Gum Dammar.t — Dr. F. L. James, referring to a paper by Mr. H. Mor- 

 landj (in which he discredits gum dammar on the ground that it is as 

 friable as chalk) says that he has used dammar for several years as a medium 

 for mounting diatoms, crystals, &c. ; in fact, to the entire exclusion of 

 Canada balsam, styrax, and all other resinous media, and with perfect 

 satisfaction. It may be used without decolorization by proceeding as 

 follows : Dissolve the dammar in sufficient benzol to give a fluid which will 

 pass through the best Swedish filtering paper. When filtered, evaporate 

 the surplus benzol, and bring the solution to the consistency of treacle. 

 Now add to each ounce of the resultant solution ten minims of the best nut 

 or poppy oil, and shake well. The result will be a " balsam " that will 

 never become brittle, turn red, or become opaque. 



Decolorized dammar may be made as follows : Dissolve dammar in benzol, 

 and to the solution (which should be filtered through absorbent cotton or 

 mineral wool) add alcohol of 95% until it no longer throws down a white 

 precipitate. Stir thoroughly, decant the supernatant liquid, and wash the 

 precipitate gum in absolute alcohol. Wash well, mulling the gum while 

 washing, and afterwards rinse with water. Throw the washed gum on 

 a filter and let dry (which it will do in twenty-four hours), after which it 

 should be dissolved in pure benzol (benzol purissima, or the crystallizable 

 benzol of Merck), and either allowed to stand a while or filtered. The 

 solution will be as limpid and clear as crystal ; but the gum contained in 

 it is excessively friable. This defect is corrected, as in the former instance, 



* Zeitschr. f. Wiss. Mikr., iv. (1887) pp. 209-10. 



t Engl. Mech., xlvl. (1887) pp. 184-5. 



i Journ. Quek. Micr. Club, iii. (1887) pp. 108-H. 



