Before releasing them, the wogs had learned their languages. They'd also tried to find out why the humanoids had so suddenly and mysteriously disappeared. Their informants had explanations, but these were contradictory and of obvious mythical origin. They just did not know the truth, though it might be concealed in their myths. Some explained the catastrophe as a plague sent by the Great Goddess or All-Mother. Others said she had sent a horde of demons to wipe out her worshippers because they had sinned against her laws. One story had it that she had shaken loose the stars so that they fell on all but a few of the people.

In any event, Yarrow did not have all the data he needed for his study. The linguist on the first expedition had had only eight months to gather his data, and a good part of that had been spent teaching several wogs American before he could really get started. The ship had stayed ten months on Ozagen, but for the first two months the crew had remained aboard while robots collected atmospheric and biota specimens, which were analyzed to make sure that the Terrans could venture forth without being poisoned or stricken by disease.

Despite all precautions, two had died of insect bites, one had been killed by a peculiar form of predator, and then half of the personnel had been stricken with a very debilitating but not fatal disease. This was caused by a bacterium which was innocuous to the natives but which had mutated in the bodies of its non-Ozagen hosts.

Fearing that other diseases might occur, and being under orders to make only a survey, not a thorough exploration, the captain had ordered a return to home. The personnel has been quarantined for a long time on a satellite station before they were allowed to touch Earth again. The linguist had died a few days after the landing.

While the second ship was being built, a vaccine for the disease was prepared. And other collected bacteria and viri were tested on animals and then on human beings who had been sent to H. This had resulted in a number of vaccines, some of which had made the crew of the Gabriel sick.