Similarly, intelligence must be displayed in deciding which of several uniformly-yielding trees should be removed. In the average sense of this consideration one must pay no attention to symmetry of spacing, but when dealing with trees of fairly uniform yields one needs to study the characteristic development of the trees individually, in order to retain those which would appear to be most favourably situated with regard to surrounding trees. CHAPTER IV _TAPPING SYSTEMS_ Broadly there are only two methods employed in obtaining the latex from _Hevea Brasiliensis_. The first is that employed in South America, where incisions are made by means of a light axe. The other is the system of excision, or paring, of the bark practised on plantations in the East. In the early days of the plantation industry, the South American method seems to have been employed, and the writer has knowledge of trees on one of our best-known estates in Malaya which still exhibit the outward and visible signs of that method. At a comparatively early stage, however, the method of excision was introduced. Curiously enough there appears to be no record of its inception or of the individual who was responsible for the substitution of this method. We have been so accustomed to regard it as one of the ordinary facts of estate procedure, that this point seems to have escaped notice and enquiry. As a variant of these two main methods, a slight vogue was for a short while obtained by the operation known as "pricking." This was generally combined with excision of bark, and was then known as the "paring and pricking" method; but the simple operation of pricking alone had its adherents, and various forms of instruments were designed to achieve the object. As a means for obtaining a flow of latex, pricking may have been effective, but the general difficulties attaching to the collection of the latex was such as to put the method out of favour. In the employment of "paring and pricking," a thin shaving of bark was excised on one occasion. At the next tapping no bark was excised, but a pricking instrument was used along the previously cut surface. It was not proved that any advantage was gained by this method, which was more commonly employed in Ceylon than elsewhere, and it would be surprising to find it in use at the present day. In the ordinary way the method of excision is practised in such a manner that the "cut" gradually descends to the base of the tree.