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 III THE PHYSIOLOGY OF LATEX PRODUCTION Rubber is derived from a milky liquid, known as latex, which occupies a special series of channels in the cortex, or inner bark of a number of different species of plants. The proportion of rubber contained in the latex varies greatly in different species. In many latices rubber is almost or entirely wanting, its place being taken by various resinous substances. The majority of the plants in which the latex contains a large proportion of rubber are either trees, or shrubs, or woody climbers. Before considering the origin and functions of latex, we propose to describe in very brief outline the structure and functions of those parts of a woody plant or tree which are directly or indirectly affected when the latex is removed by the operation of tapping. Tfa Structure and Functions of the Vegetative Organs. What are known as the vegetative organs of a tree, as opposed to the organs specially concerned with reproduction, may be divided into leaves, stem and roots. The functions of the roots—to take the lastmentioned organs first—are, firstly, to hold the tree firmly upright by anchoring it in the soil; and secondly, to absorb certain substances contained in the soil which are essential for the nourishment of the plant Among the most important of these substances, in addition to water, are various compounds of nitrogen, phosphorus and potash. Before these substances can be utilised as food by the different parts of the plant, it is necessary for them to be altered and in most cases combined with the still more important substance carbon, which is only obtained through the leaves. One of the most important functions of the leaves therefore is to absorb carbon from the atmosphere in the form of carbonic acid gas. The functions ...