THE MICROSCOPE. 



soak it in water for a time ; tear it in pieces with a 

 pair of needles, and examine under the microscope 

 with reflected light, you will see a great number of 

 glistening fibres. It seems probable that the use of 

 these spiral vessels is to convey air to the plants, thus 



Fig. 5 Spiral Vessels. 



Fig. 6. 



forming a system of internal respiration, which at once 

 suggests an analogy to that of insects, the tracheae of 

 which very closely resemble the spiral vessels in the 

 vegetable kingdom. Spiral vessels, however, are some- 

 times found to convey fluid. The various kinds of 

 ducts, or the canals through which fluids are carried 

 to different parts of plants, will form objects for study ; 

 spiral, annular, dotted, scalariform, and reticulated 

 ducts are interesting varieties of form. 



Among other important organs, the stomata, or little 

 openings by which almost all leaves with distinct 

 cuticles are perforated, must be mentioned. These 

 organs are really mouths through which respiration 



