Page:Austin Freeman - The Mystery of 31 New Inn.djvu/53

 medical aspects of the case. The first question that confronts us is that of sleeping sickness, or negro-lethargy as it is sometimes called; and here we are in a difficulty. We have not enough knowledge. Neither of us, I take it, has ever seen a case, and the extant descriptions are inadequate. From what I know of the disease, its symptoms agree with those in your case in respect of the alleged moroseness and in the gradually increasing periods of lethargy alternating with periods of apparent recovery. On the other hand, the disease is said to be confined to negroes; but that probably means only that negroes alone have hitherto been exposed to the conditions that produce it. A more important fact is that, as far as I know, extreme contraction of the pupils is not a symptom of sleeping sickness. To sum up, the probabilities are against sleeping sickness, but with our insufficient knowledge, we cannot definitely exclude it."

"You think that it may really be sleeping sickness?"

"No; personally I do not entertain that theory for a moment. But I am considering the evidence apart from our opinions on the subject. We have to accept it as a conceivable hypothesis that it may be sleeping sickness because we cannot positively prove that it is not. That is all. But when we come to the hypothesis of morphine poisoning, the case is different. The symptoms agree with those of morphine poisoning in every respect. There is no exception or disagreement