TJIE WAY 'lO SEE THEM. o7 



object whatever is more completely defined. 

 Those persons who have not seen them, cannot 

 do better than to cut with a pair of scissors a 

 small bit from the leaf of the plant called St. 

 John's wort. Place this little fragment on a 

 slip of glass, with the under side, in which the 

 stomata abound, uppermost. Take a good 

 half-inch achromatic object-glass, and put on 

 the speculum. Throw the light on with the 

 mirror attached to the microscope, and view 

 the leaf with an appropriate eye-piece. To the 

 astonishment of every one witnessing this 

 sight for the first time, the whole surface will 

 appear closely studded with the stomata. 

 Some will be found open, others shut ; but 

 the whole will be seen with the utmost dis- 

 tinctness. Ever after, the use of the term will 

 present no difficulty ; and if other leaves and 

 stems be submitted to a similar inspection, 

 whatever is said relative to these minute 

 organs will become intelligible. A practised 

 microscopist will show them admirably by 

 scraping off a slight morsel of the cuticle of a 

 leaf, and putting it on a piece of glass with a 

 slip of very thin glass over it. The power 

 then used should be one-eighth of an inch. 

 The location of the spores of mildew in wheat 



