Howler monkeys, toucans and parrots above. . .that is the groundview of lowland rain forest--jungle, infinitely more colorful and varied is the leaf canopy 100 feet above, shielding the ground and grabbing the sun's rays that energize the jungle life cycle. It is this canopy that field biologist Perry chose as his scholarly niche as a young graduate student in California, and the same, in a Costa Rican jungle, that he brings marvelously to life. Perry chose as his first tree to climb a majestic espavel, a relative of the cashew nut, 120 feet high and 10 feet across. Like many jungle giants, it lacked lower limbs so that the climb entailed shooting a rope over a high branch. The climb was a dirty one: a machete was needed to hack away at foot-thick encrustations of ferns and mosses. But the rewards are the abundant orchids, birds, insects, small mammals and other species that abound in the canopy. The tree turns out to be hollow so on the next trip Perry decides to explore it--notwithstanding his own fear. His descent into stench-filled blackness is guranteed to create frissons in the reader as well, as he encounters spiders, bats, termites, fungi and other creatures that abide in darkness or derive sustenance from the wood itself. Perry is interested in detailing how the system works--an ecology that efficiently recycles detritus from above to the ground to feed the roots and other ground life and maintain the tree. Perry is interested in who pollinates what in this system and in pursuing this question introduces yet another theory to counter the controversial extraterrestrial-death-of-dinosaurs theory: here, flowering plants proved extraordinarily successful, displacing the bymnosperms (naked seed plants) and the herbivorous dinosaurs that lived on them. As the dinosaurs subsided over millions of years, mammals began their ascendency, eventually leading to the canopy-dwelling primates that are ancestral to man. Will there be canopy to survive? Perry sounds the alarm that population encroachments seriously threaten nearly all jungle terrain in the world today. So in addition to the intrinsic ecology-exploration charms of the book, it also serves to sensitize readers to the need to conserve one of nature's great wonders.