Tarzan and the Waziri realized at once that it was a small and harmless party, and even Nkima, who had retreated to the safety of a near-by tree, showed his contempt by scampering fearlessly back to climb to the shoulder of his master. "Doctor von Harben!" exclaimed Tarzan, as the bearded stranger approached. "I scarcely recognized you at first." "God has been kind to me, Tarzan of the Apes," said von Harben, extending his hand. "I was on my way to see you and I have found you a full two days' march sooner than I expected." "We are after a cattle-killer," explained Tarzan. "He has come into our kraal several nights of late and killed some of our best cattle, but he is very cunning. I think he must be an old lion to outwit Tarzan for so long. "But what brings you into Tarzan's country, Doctor? I hope it is only a neighborly visit and that no trouble has come to my good friend, though your appearance belies my hope." "I, too, wish that it were nothing more than a friendly call," said von Harben, "but as a matter of fact I am here to seek your help because I am in trouble--very serious trouble, I fear." "Do not tell me that the Arabs have come down again to take slaves or to steal ivory, or is it that the leopard men are waylaying your people upon the jungle trails at night?" "No, it is neither the one nor the other. I have come to see you upon a more personal matter. It is about my son, Erich. You have never met him." "No," said Tarzan; "but you are tired and hungry. Let your men make camp here. My evening meal is ready; while you and I eat you shall tell me how Tarzan may serve you." As the Waziri, at Tarzan's command, assisted von Harben's blacks in making their camp, the doctor and the ape-man sat cross-legged upon the ground and ate the rough fare that Tarzan's Waziri cook had prepared. Tarzan saw that his guest's mind was filled with the trouble that had brought him in search of the ape-man, and so he did not wait until they had finished the meal to reopen the subject, but urged von Harben to continue his story at once. "I wish to preface the real object of my visit with a few words of explanation," commenced von Harben. "Erich is my only son. Four years ago, at the age of nineteen, he completed his university course with honors and received his first degree. Since then he has spent the greater part of his time in pursuing his studies in various European universities, where he has specialized in archaeology and the study of dead languages. His one hobby, outside of his chosen field, has been mountain-climbing and during succeeding summer vacations he scaled every important Alpine peak. "A few months ago he came here to visit me at the mission and immediately became interested in the study of the various Bantu dialects that are in use by the several tribes in our district and those adjacent thereto.