For some time our spirited little animals went willingly enough, but at length they both began to flag, and on looking down I saw that their heads and necks had begun to swell. The swelling increased until they were fearfully disfigured, while their nostrils and gums became swollen, and discharged a clear mucus. Still on they went, though their pace became slower and slower, and it was evident that they could only walk with the greatest difficulty. At last we were obliged to dismount, lest they should roll over with us on the ground. On looking at them we found that their eyes were glassy, the pupils greatly dilated, while the hair on their backs seemed literally to stand on end. To mount again would have been useless, but unwilling to abandon them, we led them forward as fast as they could move. Mr Tidey constantly stood up looking out more anxiously than ever for the fort, but no object broke the line of the horizon to the westward. Sometimes we thought that we might possibly have passed it, and then we hoped against hope that we should reach it even now before dark. Still the day wore on, and our poor horses followed us with feeble steps, and it was pitiable to look at them, so swollen and disfigured had they become, their faces resembling hippopotami rather than terrestrial steeds. At last Dio's stumbled and fell; nothing which we could do would induce the poor creature to rise, so we were obliged to leave him to become ere long the prey of the coyotes, should they venture to devour a poisoned animal. Mine, which had perhaps not received so much of the venom in its system as the other, still followed me, but it moved so slowly that I was compelled to lag behind my companions. The sun set and still nowhere could we discover the fort; there seemed every probability that we should have to spend another night on the open prairie, without fire, food, or shelter, or a drop of water to quench our thirst. That my poor animal could survive appeared impossible, and even Mr Tidey's horse suffered greatly. "It seems doubtful whether my poor brute will be able to move a leg to-morrow, and if so, we shall all three have to trudge forward on foot," he observed. "Then I would advise you to gallop on at once while there is any daylight, and perhaps you may reach the fort and be able to send us help," I answered. "No, no, I cannot leave you and Dio alone on the prairie. Should any harm happen to you I should never forgive myself," he answered. "But by going on alone you may obtain assistance, and in reality serve us more than by remaining behind," I replied. Still I could not persuade the Dominie to desert us, and we trudged on as before.