PRACTICAL MICROSCOPY. 



stems of trees and shrubs, the pine, fir, hornbeam, box, 

 birch, beech, oak, chestnut, and elder, being easily ac- 

 cessible, are interesting when cut into sections. The leaves, 

 seed, pollen, roots, hairs, cuticles, raphides, and a host of 

 other preparations, may be obtained from almost any plant, 

 whether it be a choice specimen from the greenhouse or a 

 common weed from the garden. 



The starches form a study in themselves, and are specially 

 interesting from many points of view ; they are easily pre- 

 pared and should be kept dry, in small homoeopathic tubes, 

 for observation. The grains, such as wheat and barley, 

 may be bruised and set aside for a few days to ferment, 

 when, upon squeezing through a fine cotton cloth, the 

 milky liquid contains the starch. Roots, rhizomes, and 

 tubers require to be rasped, and the milky fluid 

 strained in the same manner. After a time, the starch 

 granules subside, when the supernatant fluid must be 

 poured off and fresh water added, the whole stirred up, 

 and allowed to settle again. After pouring off the water, 

 the granules should be allowed to drain upon blotting- 

 paper and dried at the temperature of the air in a warm 

 room. Fig. 145 shows several of the commoner forms of 

 starch. 



Nothing special is required for the collection of raw 

 material for vegetable preparations, without it be a tin 

 case, for holding leaves, stems, or the whole plant, and 

 squares of soft tissue paper, in which to carefully fold 

 specimens. In collecting pollen, it is well to gather the 

 complete flower, and carefully isolate the specimens in 

 order that no confusion of the granules may take place. 

 The pollen of a species of the mallow tribe is often used 

 as a test object for low-power objectives. It is shown in 



Fig- 97- 



Works which may be consulted : Ma6t and Decaisne's 



