136 MICROSCOPIC OBJECTS. 



during the process. The specimens should be small ; 

 half- inch cubes are quite large enough. The top and 

 bottom should be carefuUy cut at right angles to the 

 direction of the woody fibres, and in exogenous woods the 

 sides must be parallel and perpendicular to the medullary 

 rays. Wlien small branches or twigs are to be cut, it is 

 only necessary to select a part clear of knots and cut the 

 top and bottom horizontal. 



On Preparing the Vascular Tissue of Plants. — The 

 spiral, dotted and reticulated vessels of plants, require 

 in most cases to be dissected out, which is to be done 

 under a shallow magnifier. A single lens of one inch or 

 one inch and a half focus will answer very well for this 

 piu'pose. Having procured a piece of asparagus, the 

 petiole of the garden rhubarb, or such other plant as it 

 may be desirable to dissect, cut out a piece about one 

 inch long, spht it open with a sharp knife or scalpel, then 

 examine it under the magnifier, and separate with a 

 needle-point any of the vessels you require from the 

 surrounding cellular tissue in which they are imbedded. 

 This process is facilitated by dropping a little water on 

 the specimen ; and to prevent the specimen moving while 

 dissecting, it should be fixed by bees' wax. Vessels, 

 ducts, and cellular tissues, when prepared, should be 

 kept in spirits of wine until mounted. 



On Preparing thin sections of Siliceous Fossils. — For 

 this purpose it is necessary to provide yourself with a 

 thin soft iron circular plate. The best size for amateurs 

 is five or six inches in diameter. Lapidaries usually 



