“Of course, like everything, it has its own peculiar dangers.  But the one point I wish to make is this:  In the selection of a donor for transfusion, people fall into definite groups.  Tests of blood must be made first to see whether it ‘agglutinates,’ and in this respect there are four classes of persons.  In our case this matter had to be neglected.  For, gentlemen, there were two kinds of blood on that laboratory floor, and they do not agglutinate.  This, in short, was what actually happened.  An attempt was made to transfuse Cushing’s blood as donor to another person as recipient.  A man suffering from the disease caught from the bite of the tse-tse fly—­the deadly sleeping sickness so well known in Africa—­has deliberately tried a form of robbery which I believe to be without parallel.  He has stolen the blood of another!

“He stole it in a desperate attempt to stay an incurable disease.  This man had used an arsenic compound called atoxyl, till his blood was filled with it and its effects on the trypanosomes nil.  There was but one wild experiment more to try—­the stolen blood of another.”

Craig paused to let the horror of the crime sink into our minds.

“Some one in the party which went to look over the concession in the Congo contracted the sleeping sickness from the bites of those blood-sucking flies.  That person has now reached the stage of insanity, and his blood is full of the germs and overloaded with atoxyl.

“Everything had been tried and had failed.  He was doomed.  He saw his fortune menaced by the discovery of the way to make synthetic rubber.  Life and money were at stake.  One night, nerved up by a fit of insane fury, with a power far beyond what one would expect in his ordinary weakened condition, he saw a light in Cushing’s laboratory.  He stole in stealthily.  He seized the inventor with his momentarily superhuman strength and choked him.  As they struggled he must have shoved a sponge soaked with ether and orange essence under his nose.  Cushing went under.

“Resistance overcome by the anesthetic, he dragged the now insensible form to the work bench.  Frantically he must have worked.  He made an incision and exposed the radial artery, the pulse.  Then he must have administered a local anesthetic to himself in his arm or leg.  He secured a vein and pushed the cut end over this little canula.  Then he fitted the artery of Cushing over that and the blood that was, perhaps, to save his life began flowing into his depleted veins.

“Who was this madman?  I have watched the actions of those whom I suspected when they did not know they were being watched.  I did it by using this neat little device which looks like a field glass, but is really a camera that takes pictures of things at right angles to the direction in which the glass seems to be pointed.  One person, I found, had a wound on his leg, the wrapping of which he adjusted nervously when he thought no one was looking.  He had difficulty in limping even a short distance to open a window.”