PREPARATION OF VEGETABLE TISSUES. 



441 



way of preparing it is by immersing the leaf in sulphuric ether for a 

 few seconds, allowing the fluid to evaporate, and then putting it up 

 dry. Dr. Inman of Liverpool suggests the following method : first 

 peel off the epidermis from the petal, which may be readily done by 

 making an incision through it at the end of the leaf, and then tearing 

 it forwards by the forceps. This is then arranged on a slip of glass, 

 : id allowed to dry ; when dry, it adheres to the glass. Place on it a 

 little Canada balsam diluted with turpentine, and boil it for an instant 

 over the spirit-lamp ; this blisters it, but does not remove the colour ; 

 then cover it with a thin slip of glass, to preserve it. Many cells will be 

 found showing the mamilla very distinctly, and the hairs surrounding its 

 base, each being slightly curved and pointed towards the apex of the 

 mamilla. It is these hairs and the mamilla which give the velvety ap- 

 pearance to the petal. 



Fibro-cellular tissue is found readily in Sphagnum or bog-moss, 

 and in the elegant creeper Cobsea scandens. In some orchidaceous 

 plants the leaves are almost entirely composed of it. A modification 

 of this form of tissue is found in the testa of some seeds, as in those of 

 Salvia, Collomia grandiflora, &c. 



The curious and interesting sporules of ferns, when ripe, burst, 

 and are dispersed to a distance ; so that they should be gathered before 

 they come to maturity, and mounted as opaque objects. The develop- 



fig. 213. Male Fern. 



ment of ferns may be observed by placing the seeds in moistened flan- 

 nel, and keeping them at a warm temperature. At first a single cellule 

 is produced, then a second ; after this the first divides into two, and 

 then others follow ; by which a lateral increase takes place. It must be 



