Aids to Microscopic Inquiry. Ill 



AIDS TO MICROSCOPIC INQUIRY.— No. VII. 



Haies of Plants. 



It is a very common tiling for tlie possessors of microscopes to 

 neglect objects of beauty and interest which are readily 

 accessible, and thus not to derive from their instruments the 

 pleasure and mental profit they can afford. Those who have 

 even a few square yards of town garden, or who have access to 

 ordinary plants, may derive much gratification from the 

 examination of the hairs of plants. 



The hairs of plants are cellular growths springing from 

 the cuticle ; so that, if the plant possesses a solid, woody stem,, 

 the hair, however hard in character, may be entirely removed 

 by pulling away a portion of the cuticle beneath it, and without 

 touching the solid stem. Thus hairs, even when prickly, are 

 distinguished from true spines, such as grow upon holly sterns^ 

 and remain after all the integuments have been removed. In 

 its simplest form, a plant-hair consists of a single straight tube 

 of small dimensions ; but jointed hairs, composed of cell added 

 to cell, in linear prolongation, are very common ; and so are 

 hairs of a still more complicated structure, beautifully branched, 

 and presenting star-shaped, or other agreeable, forms. 



In vegetable structure we continually notice that certain 

 cells are strengthened by a layer or layers of internal deposits. 

 Cherry-stones, vegetable ivory nuts, and innumerable other 

 substances, are composed in this way. These strengthening 

 deposits may be of a character allied to woody tissue (sclerogen) 7 

 or may consist of mineral matter, such as the silex found in 

 the outer layers of straw, canes, etc. A hair stiffened in this 

 way becomes a bristle, or a stiff scale. Ordinary hairs are soft, 

 delicate structures, with fluid contents, the rotation of which 

 may be seen with a sufficiently high power. Cabbage- leaves 

 offer good specimens of single hairs, conical in form. Beautiful 

 star-shaped hairs cover the leaves of the Alyssum, common in 

 all gardens ; and, in fact, plants by the dozen might be named 

 in which the hairs are well worth examination. We shall 

 select a few we have picked from very accessible plants. 



First, if we take an ivy-leaf — a young bright green one 

 being the best — and turn it with the under side upwards, we 

 have a beautiful object for an inch or two-thirds object-glass. 

 We see groups of hairs springing from a common base, and 

 stretching out somewhat like the arms of a star-fish. This 

 object should be viewed by reflected light, and then some of 

 the hairs, removed with a portion of the cuticle on the point of 



