10, 11.] DEPARTMENTS OF SCIENCE. 1 1 



with the lens, a needle in a handle, a penknife, and 

 tweezers are required for dissection. 



8. The compound microscope is undoubtedly a 

 higher aid in scientific investigation than any other 

 instrument of human invention. It is like the bestow- 

 ment of a new sense, or the opening of a new world. 

 Through this, almost solely, all our knowledge of the 

 cells, the tissues, growth, fertilization, etc., is derived. 

 The skillful use of this noble instrument is itself an 

 art, which it is no part of our plan to explain. 



9. On the preparation of botanical subjects for examination we remark : 

 the field of view is small, and only minute portions of objects can be seen at 

 once ; the parts must be brought under inspection successively. 



10. The tissues of leaves, etc., are best seen by transmitted light. They 

 are to be divided by the razor or scalpel into extremely thin parings or cut- 

 tings. Such cuttings may be made by holding the leaf between the two 

 halves of a split cork. They are then made wet and viewed upon glass. The 

 stomata are best seen in the epidermis stripped off ; but in the Sorrel-leaf 

 (Oxalis violacea) they appear beautifully distinct upon the entire leaf. 



11. Woody tissues, etc., may be viewed either as opaque or transparent. 

 Sections and cuttings should be made in all directions, and attached to the 

 glass by water, white of egg, or Canada balsam. To obtain the elementary 

 cells separately for inspection, the fragment of wood may be macerated in a 

 few drops of nitric acid added to a grain of chlorate of potassa. Softer 

 structures may be macerated simply in boiling water. 



CHAPTER II. 



DEPARTMENTS OF SCIENCE. 



12. Three great departments in nature are univer- 

 sally recognized: the mineral, vegetable, and animal 

 kingdoms. The first constitutes the Inorganic; the 

 other two, the Organic World. 



13. A mineral is an inorganic mass of matter 

 that is, without distinction of parts or organs. A 



