22 CENTRAL AMERICAN RUBBER TREE. 



flower clusters. Plate IV, from a photograph made near Panzos, 

 Guatemala, shows scales much larger and more closely appressed than 

 Plates V and VI, from photographs taken on La Zacualpa estate near 

 Tapachula, Mexico. The difference is especially noticeable along the 

 margins of the valves, where the scales of the Soconusco specimens 

 are smaller and more numerous and project more than the others, as 

 will be seen by a comparison of the plates. 



The pistillate or female flower clusters of Castilla (PI. VI) are flat- 

 tened in the other direction, and might be described as broadly top- 

 shaped. They are covered with scales much coarser than those of 

 the staminate flowers, and numerous two-parted styles are exposed 

 in the middle. 



As the fruits approach maturity they enlarge and spread apart until 

 the scales which formed the sides of the young flower cluster are car- 

 ried back underneath to furnish a base for the rounded-pyramidal 

 orange-colored ripe fruits (PI. VII). The number of fruits which are 

 able to mature varies between 15 and 25, and these are surrounded by an 

 equally variable number of more or less aborted fruits, which shade off 

 into scales by imperceptible gradations. At the rounded or truncate 

 apex of the fruit is a minute cavity in which the withered remnants 

 of the two-parted style are usually to be found. 



The scales of the flower heads are velvety, with small and very 

 numerous hairs, but the hairs of a few scales near the point of attach- 

 ment are much coarser. The fruits are also very finely pubescent or 

 velvety, the hairs being still more numerous and shorter than those of 

 the scales. 



The flesh of the fruit of Castilla contains numerous delicate libers. 

 It has a faintly sweetish taste, but is without appreciable flavor. The 

 removal of the pulp leaves an ivory-white seed about the size and 

 shape of the chick-pea or garbanzo (Cici r arietinum), but more regular 

 in shape. The white outer wall of this seed is thin and becomes brit- 

 tle as soon as it has dried a little. Underneath it is a still more deli- 

 cate brown coat, marked with branching lines of lighter brown. The 

 seed itself consists of two somewhat hemispherical cotyledons, with a 

 very small plumule near the more pointed end. 



It is doubtless owing to their very thin walls and rather fleshy tex- 

 ture that the seeds of Castilla dry out very easily and are accordingly 

 very short-lived. The fruits ripen and fall to the ground at the end 

 of the dry season, and the pulp assists in keeping the seeds moist until 

 the beginning of the rainy season brings conditions favorable for their 

 germination. 



The milk of unripe fruits. — At present the rapid increase of rubber 

 plantations renders the seeds valuable, but it is still permissible to raise 

 the question whether the milk with which the unripe fruits abound 



