i 



STAINS, ETC. 



1367 



CEMENTS AND VARNISHES 



TABLE OF STAINS, 



FLUIDS FOR FIXING AND HARDENING, MEDIA FOR EXAMINATION AND PRESERVA- 

 TION, ETC., AND METHODS EMPLOYED IN BIOLOGIC INVESTIGATION. 



PAGE 



teaching fluids 1367 



'ell mounts 1367 



"ements and varnishes, 1367 



leaning slides and covers, 1368 



Searing agents 1368 



"orrosion methods, 1369 



lover-glass preparations 1369 



Cytologic methods, 1369 



INDEX. 



Decalcifying fluids, 1371 



Decolorizing, etc., solutions, .... 1372 



Dissociating fluids 1372 



Embedding 1373 



Embryologic methods, 1375 



Examination of blood, 1376 



Examination and preservation 



media, 1377 



PAGE 



Fixatives, . . . 13S0 



Fixing and hardening fluids, .... 1381 



Injection masses, 1384 



Staining of con. and other tissues, . . 1386 

 Staining of microorganisms, .... 1387 



Staining of nerve-tissues, 1392 



Staining reagents, 1397 



Zoologic methods, 1405 



BLEACHING FLUIDS. 

 Hiese are used to dissolve and decolorize organic pig- 

 ments in tissues containing them, and to overcome 

 the staining of objects treated with osmic acid. 

 Chloroform, combined with nitric acid, will clear 

 strongly pigmented chitin. Grenadier's Mixture. 

 For the eyes of Arthropods and other animals. Mix 

 I part of glycerin with 2 parts of 80 per cent, alcohol, 

 and add 2 or 3 drops of hydrochloric acid. This fluid 

 dissolves pigment, while at the same time a stain is 

 formed which, in the course of from 12 to 24 hours, 

 colors the nuclei. The object may be previously 

 stained with borax-carmin. The carmin does not wash 

 out as rapidly as the pigment, but the decolorization 

 must be watched. Hydrogen Dioxid {Hydrogen 

 Peroxid, Oxygenated Water). The sections, fast- 

 ened on slides, are placed in a 10-volume, or 2 per 

 cent, solution. The melanin is reduced to a pale- 

 yellow color in from 6 to 48 hours, according to the 

 amount of pigment present and the light to which the 

 specimen is exposed (strong sunlight materially hastens 

 the process). If the treatment is continued longer 

 the coloring-matter can be entirely removed, and by- 

 watching the process a little carefully the decoloriza- 

 tion can be stopped at any point before absolute re- 

 moval. Practically it has been found to be of advant- 

 age to leave sufficient color to mark the position of the 

 pigment-cells. The liquid does no appreciable injury 

 to the structural elements. See also Pouc/iet's Mixture. 

 Javelle Water. See Corrosion fluids, Eau de Javelle. 

 Labarraque's Solution. See Corrosion-fluids , Eau 

 de Labarraque. Mayer's Chlorin-solution. To 

 remove the staining that occurs as a result of treat- 

 ment with osmic acid. The specimen is put in from 

 70 to 90 per cent, alcohol ; the bottom of the vessel 

 is then covered with crystals of potassium chlorate. 

 and a few drops of strong hydrochloric acid are added 

 by means of a pipet. The appearance of a green color 

 indicates the evolution of chlorin, which should be 

 diffused through the alcohol by shaking the vessel. 

 Objects are bleached in half a day. Nitric acid may 

 be used instead of hydrochloric, in which case the 

 bleaching agent is the freed oxygen. Marsh gener- 

 ates chlorin in a small bottle, and conveys it bymeans 

 of glass tubing to the bottom of a bottle containing the 

 sections in water. Pouchet's Mixture. Treat the 

 tissue with glycerin to which hydrogen dioxid has 

 been added — 5 or 6 drops to from 5 to 10 c.c. of gly- 

 cerin. Osmium preparations may be bleached in 

 this mixture. The same author recommends creasote 

 as a solvent and decolorizer for granular animal pig- 

 ments. Sargent's Chlorin-solution. For bleach- 

 ing insects, and suitable only for the preparation of 

 the hard parts. The solution consists of 2 grams of 

 potassium chlorate, 10 drops of hydrochloric acid, 



and water, 30 c.c. Soak the objects for two days and 

 then wash thoroughly. 



CELL-MOUNTS. 



Balsam-paraffin for Cells (Julien). This substance 

 consists of paraffin saturated with balsam-cement, and 

 is prepared as follows : Reduce commercial Canada 

 balsam to a wax-like consistence by slow evaporation 

 in a shallow tin pan over a low flame. Test by cool- 

 ing a few drops from time to time. Melt slowly a 

 quarter of a pound of paraffin, with a melting-point 

 above 45 C. (113 F.), add a lump of the balsam- 

 cement about the size of a marble, and then digest at 

 gentle heat, stirring frequently, for about an hour. 

 The appearance of a slight, yellow tinge indicates the 

 saturation of the paraffin by the balsam. When it is 

 desired to prepare a cell, the balsam-paraffin is cau- 

 tiously heated to the melting-point in a shallow porce- 

 lain capsule. These paraffin cells are suitable for 

 dry or liquid mounts, excepting for the latter when 

 Canada balsam, dammar, or oils are used as preserva- 

 tives. The great advantage of the balsam-paraffin is 

 its chemic indifference to the reagents employed in 

 the preservation-media. Paper-cell Method (Lee). 

 By means of a punch cut out a ring of paper, one 

 mm. in breadth and about one mm. smaller in 

 diameter than the cover-glass. Moisten this paper 

 circlet with the mounting-fluid and center it on the 

 slide. Fill the cell thus formed with the mounting- 

 fluid ; place the object in it; put on the cover; fill the 

 annular space between the paper and the margin of 

 the cover with glycerin-jelly, and as soon as this has 

 set turn a ring of Bell's cement on it. For Mounting- 

 media. See under Mounting. 



CEMENTS AND VARNISHES. 



These substances are chiefly used for sealing fluid 

 mounts, to prevent the admission of air and evapora- 

 tion of the liquid. Before applying a cement, all fluid 

 mounts should be ringed with glycerin-jelly, to avert 

 " running in." Amber Varnish. Fuse 6 lbs. of clear, 

 pale amber, add 2 gallons of hot clarified linseed-oil, 

 boil until the mixture " strings," and when partially 

 cooled add about 4 gallons of turpentine. Behrens 

 recommends this cement for its extreme tenacity. 

 Apathy's Cement. Heat together, in a porcelain 

 capsule, equal parts of hard paraffin (6o° C. melting- 

 point) and Canada balsam, until the mixture assumes 

 a golden tint and no longer emits vapors of turpentine. 

 On cooling, this forms a firm mass, which for use is 

 warmed, and applied with a glass rod. This cement 

 is suitable for closing glycerin mounts. Asphalt 

 Varnish. This is one of the best media, used either 

 as a cement or as a varnish. Kitton advises asphalt 





