MICROSCOPIC OBJECTS. 15 



Fig. 29. Stellate Hairs from the Ivy (Hedera Helix), x 90. 



These hairs are drawn as shown under the parabolic 

 reflector, and illustrate the stellate form of vegetable hairs. 

 The hairs are taken from the stem of the Ivy, on which they 

 may be seen in great abundance. They appear to consist of 

 groups of simple hairs joined at one end, so as to produce an 

 irregular stellate form. These hairs are compound, being 

 composed of three or more simple hairs, supported on a short 

 footstalk. There are many forms of compound hairs (see 

 figs. 28, 30, 31, &c.) . Some hairs, when young and uninjured, 

 are very favourable objects in which to observe the rotation 

 of the protoplasm or cell-contents. 



Vegetable hairs are best seen when mounted in liquid. 



Fig. 30. Hairs from Tobacco-plant (Nicotiana Tabacum), 



x!20. 



This object is drawn as seen under the parabolic reflector. 

 Tobacco is often largely adulterated with Dock, Cabbage, 

 Coltsfoot, &c., most of which plants have simple forms of 

 hair (see fig. 33), and may thus, under the microscope, be 

 distinguished from the true Tobacco-leaf or stalk, which has 

 compound hairs with a knob at the apex. Most of the hairs 

 are of a rather large size. 



The best plan to mount this object is to boil a piece of the 

 stem of the plant in weak nitric acid, say acid 1 part, water 

 3 parts, when the cuticle will be seen to separate, and may 

 then be mounted in glycerine, or, what is better, alcohol and 

 water. 



