The Anatomy of Euphorbia Intisy^

Among the many peculiar plants that characterize the arid region of southern Madagascar, one of the most interesting is Euphorbia intisy? Not only does this plant present several characteristics that make it worthy of considerable study by the theoretical botanist, but its past performance as a rubber-producing plant makes it seem possible that it may prove adaptable to American conditions. Euphorbia intisy was discovered June 7, 1891, at Tsivory, Madagascar (S, p. 107-109)? Commercial exploitation followed at once, so that the annual rubber exportation of Madagascar rose from less than 50,000 pounds to almost a million pounds. The ruthless exploitation, however, soon showed its effect, for within a few years intisy had become so rare that Prudhomme {10) in 1899, even before the plant had been named botanically (4), reported that where intisy had formerly been very common it was already difficult to find specimens. The manner of obtaining intisy rubber is very simple and is one of the factors that have led to the commercial disappearance of this plant. The latex, which exudes from any cut, coagulates in the air without further treatment. Hence all that the native has to do is to make cuts in the stem, return after a few hours or a few days and pull off bands of rubber of very high quality, which he wraps into balls. The yield of rubber from stems less than 3 cm. in diameter is so slight that it does not pay to tap them. Consequently, at the present time, because of the disappearance of the large trees, one finds tapping scars only at the collar, the most favored tapping position. (Fig. 1.) It is reported, however (^), that during the time of its great exploitation spiral cuts were made all the way up the tree from the ground to branches as small as 2 or 3 cm. in diameter, 15 pounds or more of rubber being obtained at one tapping from a single tree. In many cases the first tapping was so severe that the tree died outright. Trees subjected to less severe tapping in some cases withstood several such onslaughts, but still the weakening—both structural and physiological—^incident upon careless cutting, always brought about the death of the tree. From what is known about tapping other rubber plants and about the stem anatomy of this plant, intisy would almost surely be able to live for many years if careful tapping methods were employed. That this valuable plant occurs throughout a large part of southern Madagascar, that it does not occur in pure stands, and that it requires