 What is the purpose of the Orthan taking over a human host?
He had blasted across trackless space to subdue a defenseless world—only to meet on Earth emotions that were more deadly than weapons. [Transcriber's Note: This etext was produced from Planet Stories Fall 1942. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] He stared appraisingly around at the luxuriant green growth of foliage further inland; and started toward the little stretch of trees and brush, walking carefully because of the lesser gravitation. Oddest of all, he wore no garments, other than the necessary belt and straps to support his rod-like weapon of white metal and his pouches for food and specimens. The Orthan entered the narrow strip of trees and crossed to the little-used highway on the other side. Here he patiently sat down to wait for an Earthman or an Earthwoman to pass. His task now was to bring a native, intact if possible, back to the carefully buried space cruiser where his two fellows and himself would drain the creature's mentality of all its knowledge. In this way they could learn whether a planet was suited for colonization by later swarms of Orthans. Already they had charted over a hundred celestial bodies but of them all only three had proven worthy of consideration. This latest planet, however, 72-P-3 on the chart, appeared to be an ideal world in every respect. Sunlight, plenty of water and a dense atmospheric envelope made of 72-P-3 a paradise among planets. The explorer from another world crouched into the concealment of a leafy shrub. Its squat body was covered with baggy strips of bluish cloth and it carried a jointed rod of metal and wood in its paw. It walked upright as did the men of Ortha. The Earthman was opposite now and he must waste no more precious time. The mighty muscles of the Orthan sent him hurtling across the intervening space in two prodigious bounds, and his hands clamped across the mouth and neck of the stranger....
 To investigate the planet without vslling attention, and determine if it's worth colonizing.
 To get the full human experience, and understand what makes the planet worthwhile.  To investigate the planet without vslling attention, and determine if it's worth colonizing.  To assimilate the human host into the Hord, and add to it their knowledge.  To examine the memories of the human host, and see what knowledge they have.