Jennings: Manual of Mosses 9 



quickly but carefully placed on the square on which the dissections are dis- 

 posed. To prevent the dissected objects from changing their position too 

 much, and to obviate the inclusion of air-bubbles, it is best to lay the square 

 which is to serve as cover so that one edge only comes into contact with the 

 other square and then let the cover settle down gradually, thus driving the air 

 out in front of the gradually advancing line of contact of the mica and mount- 

 ing medium. The slide is now ready for study under the compound micro- 

 scope and after this it may be placed in the paper pocket along with the speci- 

 mens from one of which the dissections were made. In order to insure greater 

 permanency of the slide, as thus made, some workers advocate sealing the slide 

 by running a little ring of Canada balsam* around the edge of the smaller 

 mica square, thus keeping the air away from the glycerine jelly and preventing 

 any further drying out. The object of placing the dissections in the ten per 

 cent solution of glycerine is to gradually allow the dissections to accommodate 

 themselves to increasing density of solutions; if the dissections were transferred 

 immediately from pure water to the melted glycerine jelly there would in 

 most cases be much shrinkage and curling, thus spoiling the slide for purposes 

 of study. In a few cases even the transferance from water to ten per cent 

 solution and thence to the jelly is too great a change and in such cases it is 

 necessary to pass the dissections through a series of solutions of increasing 

 glycerine per cent, up to a strong solution, before using the glycerine-jelly. 

 Another way is to place the dissections in weak glycerine solution and keep 

 adding more solution as the water evaporates from the first, thus gradually 

 increasing the density. 



Another method has been described by Steyaert, R. L. (Science 105: 47-48. 

 1947) . Chloraphenol, consisting of two parts chloral hydrate and one part 

 phenol crystals,** is heated till liquefied and then kept in dropping bottles. This 

 liquid mixes with either water or Canada balsam. Dried material may be 

 placed and dissected directly in a mixture of two drops of chloraphenol to one 

 of balsam dissolved in xylol. After this, place the cover slip on and gently 

 heat to evaporate the chloraphenol, in the meantime placing droplets of balsam 

 at the edge of the cover slip so that it may flow under and ensure a sufficient 

 amount of balsam in the mount. The mount may then be sealed (ringed) 

 with varnish. 



Or, material may be dissected in water which may then be drawn out by a 

 blotter while chloraphenol is run under the slip from the opposite edge. 

 Slightly warming the slide helps to get rid of air bubbles. The chloraphenol 

 may then similarly be drawn out with a blotter while balsam is drawn under 

 from the other side of the slip. When thoroughly filled with balsam the amount 

 may be permanently ringed with varnish. 



* Before applying such a sealing medium, the edges of the slips should be dry. 

 Other sealing media often used are gum dammar, shellac varnish, gold size, or m.^rine 

 glue. 



** Care must be taken not to let the fjhenol come into contact with the skin. It will 

 (a use a very severe bum. 



