[*] It was probably an oryx.
When he turned with his booty to go home, he noticed a little fawn which stood on a knoll above him, looking at him. She stood quite still, so shaded off against the grasses that only a lucky eye could distinguish her. She was waiting, perhaps, for him to go away, so that she might call her mother. She made no effort to run from him. Something in her appearance made him think that she was ill. The carriage of her head seemed queer. Her coat had a look of staring. He wished then, that he had brought his glasses, so that he might examine her narrowly. Moving round a little, he made sure that her coat was in poor condition. He judged that she might have been mauled by a beast of prey.
He was just about to move on when a thought occurred to him. What if the young of the wild game should not be immune? What if the bite of the infected tsetse should set up a mild form of nagana in them from which they recover? What if that mild sickness should confer a subsequent immunity on the inflicted individual? Surely the result would be obvious. "Vaccination" with the blood of the afflicted calf or fawn would set up a mild attack of the disease in man, and, perhaps, give him subsequent immunity from more virulent infection. The ailments of wild animals are few. What if this fawn should be suffering from a mild attack of the disease? He crept a little nearer to her, bending low down to see if he could see the swellings on the legs and belly which mark the disease in quadrupeds. He could not be sure of them. He could only be sure that the coat was staring, and that the nose and eyes were watery. He whistled gently to the little creature, hoping that she would be too young to be frightened of him. She stared at him with wide eyes, trembling slightly, flexing her ears. He whistled to her again. She called plaintively to her dam. She lowered her little head, ready to attack, pawing the ground like a warrior. Roger fired. Afterwards he felt as though he had killed a girl.
He returned to "Portobe" weighted down with jars, which he emptied carefully into sterilised pans. The result made "Portobe" look like a cannibal's dairy. An examination of the blood shewed that both animals had harboured trypanosomes in large numbers. When the blood had coagulated, he decanted the serum into sterilised bottles, to which he added minute quantities of antiseptic. That operation gave him his serum. He had now to test it for bacteria and for toxins. He added a portion from each bottle to various culture-mediums in test-tubes. He added these test portions to all his media, to glycerine-agar and glucose as well as to those better suited to the growth of trypanosomes.
He set them aside to incubate.
If there were bacteria in the sera they would increase and multiply on the delightful food of the media. When Roger came to examine the media, he came expecting to find them swarming with bacteria of all known kinds. He was naturally vain of the success of his hunting; but he knew that crude surgery out in the open is not so wholesome a method of obtaining serum as might be. Still, a close examination shewed him that the cultures had not developed bacteria. He was pleased at this; but his pleasure was dashed by the thought that it was rather too good to be true. He might have muddled the experiment by adding too much disinfectant to the sera while bottling, by using cultures which had in some way lost their attractiveness, or by some failure in the preparation of the slides. After going through his examination the second time, he decided to proceed. He injected large doses of the sera into two monkeys.
Again he was successful. The monkeys shewed no symptoms of poisoning. The sera, whatever they might be, were evidently harmless to the "homologous" animal. But the success made Roger even more doubtful of himself. It made him actually anxious, lest in adding disinfectant to the sera, he should have destroyed the protective forces in them, as well as the micro-organisms at which he had aimed. He delayed no longer. He injected Lionel with a large dose of the serum from the grown animal; he injected himself with the serum from the fawn. Going down to the village, he made a minute examination of those who were the least ill. Choosing out those who shewed no outward signs of the congenital or acquired forms of blood-poisoning, he injected them with sera, thinking that if they recovered he would use their sera for other cases. For his own part, he felt better already. The excitement of hope was on him. He had risen above his body.
For the next few days his life was a fever of hope, broken with hours of despair. One of his patients died suddenly the day after the injection. Lionel seemed no better. Another patient seemed markedly worse. He repeated the doses, and passed a miserable morning watching Lionel. The evening temperature shewed a marked decrease. An examination of the throat glands shewed that the trypanosomes had become less waggish. They were bunching into clumps, "agglutinising," with slow, irregular movements. That seemed to him to be the first hopeful sign. On studying his books he could not be sure that it really was a good sign. One book seemed to say that agglutination made the germs more virulent; another that it paralysed them. He could see for himself that they had ceased to multiply by splitting longitudinally. And from that he argued that their vitality had been weakened.
The next day Lionel was better; but the native patients were all worse. They were alarmingly worse. They shewed symptoms which were not in the books. They swelled slightly, as though the skin had been inflated. The flesh seemed bladdery and inelastic at the same time. The pigment of the skin became paler; the patients became an ashy grey colour. The blood of one of these sufferers killed a guinea-pig in three hours. After a short period of evident suffering they died, one after the other, apparently of the exhaustion following on high fever. Roger, in a dreadful state of mental anguish, stayed with them till they were dead, trying remedy after remedy. He felt that he had killed them all. He felt that their blood was on his hands. He felt that all those people might still have been alive had he not tried his wretched nostrum on them. There was no doubt that the sera had caused their deaths. Those who had had no serum injections were no worse than they had been. He wondered how long it would be before these symptoms of swelling and high fever appeared in himself and Lionel. He went back to "Portobe" expecting to find Lionel in high fever, going the road to Marumba.
He found Lionel weakly walking about outside the tent, conscious, but not yet able to talk intelligibly. He had not expected to see Lionel walk again. The sight made him forget the deaths down in the village. He shouted with joy. Closer examination made him less joyous. The skin of Lionel's arm, very dull and inelastic to the touch, was slightly swollen with something of the bladdery look which he had noticed in the men now dead. It was as though the body had been encased in a bladdery substance slightly inflated. He had no heart to test the symptoms upon the body of another animal. There was death enough about without that. He sat down over the microscope and examined his sera again and again. He could find no trace of any living micro-organisms. The sera seemed to be sterile. But he saw now that it had some evil effect upon those infected with trypanosomes. He could not guess the exact chemical nature of the effect. It probably affected the constituents of the blood in some way. The poison in the sera seemed to need the presence of trypanosomes to complete its virulence.