74 THEMICROSCOPIST. 



are attached to and envelope the seeds. Hairs are composed 

 of cellular tissue. Their functions are said to be either lym- 

 phatic or secreting. They offer great varieties in form, some 

 being stellated, others forked or branching. The hairs of Vir- 

 ginian spiderwort (Tradescandia Virginica), the sting of the 

 Nettle (Jjrtica dioica), and the radiating scale or hair in 

 Eloeagnus, the Oleaster, are interesting specimens. 



Pollen may be mounted in Canada balsam; or, if rather 

 transparent, in fluid; or dry. Sometimes the grains are inte- 

 resting opaque objects. The common form of the pollen or 

 farina of flowers is spherical, with a smooth, punctured, or 

 spiny surface; but some are square, others cylindrical, oval with 

 attenuated extremities, or triangular with convex sides. The 

 pollen of the passion flower is very curious, and if immersed 

 in very diluted sulphuric acid opens and disperses the grains. 

 The pollen of Datura stramonium, or Jamestown weed, and 

 others, when immersed in a few drops of weak acid placed 

 upon a slide under the microscope, emits a tube of some 

 length. The granular matter in the pollen may then be seen 

 to pass along the tube until the pollen is emptied. The Diameter 

 of the pollen varies considerably in different plants; among the 

 smallest are those of the Sensitive Plant. 



Starch. The granules of starch (not the ordinary impure 

 starch of the laundress) obtained from different plants, are 

 found, when examined under the microscope, to differ in size 

 and form. Some are spherical, others elliptical, flask-shaped, 

 polyhedral, &c. Hence this method of examination affords a 

 ready means of detecting fraud in the substitution of one kind 

 of grain for another. Starch granules, although so very minute, 

 are composed of a fine and delicate membrane, enclosing a 

 fine mealy powder. It may be compared in some respects to a 

 common pea, in which the legumen is enclosed in a testa or 

 skin. Starch granules are not soluble in cold water, nor is 



