Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER I. ON SOME OF THE CONDITIONS AFFECTING THE LIFE OF PLANTS. Section A. Respiration. Section B. Temperature- Poisons—Electricity. Section A. Respiration. The presence of free oxygen is a necessary condition of the life of all the higher plants. This fact will be more conveniently demonstrated in the chapters on growth and growth-curvatures. The present section is intended as an introduction to the study of the facts without special reference to the importance of respiration. (1) Production of C03. Take a stoppered jar of about 500 c.c. capacity, fill it to one-third of its height with (in spring) horse-chestnut buds or (in winter) with beans which have been soaked in water for 12 hours and have been afterwards placed in damp cocoa-fibre for 12 hours. Place the jar in a warm room, and after 12—24 hours cautiously open the jar and lower a lighted taper which will be extinguished as it enters the COa produced. U. A. 1 (2) Absorption of C0t by Potash. Take a filtering flask of 400 or 500 c.c. capacity,, having a lateral opening as shown in fig. 1, to which a Fig. 1. Exp. 2. glass tube, A (4 or 5 mm. bore), is attached by thick rubber tubing and wire ties. The end of A dips into the mercury' in the beaker Hg. The flask contains enough .germinating barley to cover a piece of wet filter-paper at the bottom of the flask. Barley germinates well in winter: it should be soaked in water for 24 hours and kept in damp air for 24 hours before use. A test-tube T half full of strong KHO is introduced into the flask, which is then closed by a sound tightly fitting rubber cork. As the C0a, produced by respiration, is absorbed by the KHO, the mercury in the beaker Hg is sucked up the tube A. In starting the experiment it is necessary to warm the air in the ...