The rubber is derived from the resinous latex or milky juice, which pours out from any wound in the bark of certain trees and creeping plants. This milk must be poisonous enough to kill the rash and intrusive mother beetle, who wishes to lay her eggs in the wood. It must be elastic, because the branches and stems swaying to and fro in the wind require a yielding, springy substance, but resin is contained in it, so that it promptly hardens and closes up the scar. The traveller Belt, in his _Naturalist in Nicaragua_, mentions that those trees which had been entirely drained of their rubber by the Indian gatherers were riddled by beetles, and in an unhealthy, dying condition. Almost all the important rubber plants are found in wet, unhealthy, tropical forests; they are by far the most important jungle product in West Africa, as well as on the Congo River and in the Amazon valley. It is quite impossible to describe the various rubber trees, and the different methods of gathering rubber, but it may be interesting to quote from an account of the method of its collection in Nicaragua, by Mr. Rowland W. Cater.[134] [134] _Chambers's Journal_, Oct. 24th, 1896. The best season for tapping the trees of _Castilloa elastica_ is from August to February. It is best also to perform the operation early in the morning before the daily rain, "or in the evening after the rain has fallen. The milk ... is white and of the consistency of cream. The tree thrives best in moist but not marshy forests. "It seeds in the tenth year, and ought not to be tapped before its eighth year, or its growth may be much retarded. "On reaching the group of trees, which numbered seventeen of various sizes, my Carib friends first cut away the twining creepers that almost hid the trunks, and then carefully removed a couple of buruchas, natural ropes of rubber, formed in the following manner: From incisions in the bark, possibly caused by woodpeckers or some insect, the juice often exudes, trickling down the trunk, in and out of the encircling creepers, and sometimes reaching the ground. The milky stream coagulates and turns black as it runs, forming a long strip or cord, with which the huléros often tie up their bales. "The parasites removed, Pete and José strapped on their espuelas (climbing spurs), fastened at the knee and ankle, and having dug a small pit or basin at the foot of each of a couple of trees, passed a ring of stout rope round the trunks and their own waists, and walked up with their machetes between their teeth. By lifting the rope at every step they were enabled to stand almost erect, and when lying back in the ring both hands were at liberty.