Aug. 25 — Batta complained of a pain in his back today — things may be developing.
Sept. 3 — Have made fair progress in my experiments. Batta shews signs of lethargy, and says his back aches all the time. Gamba beginning to feel uneasy in his bitten shoulder.
Sept. 24 — Batta worse and worse, and beginning to get frightened about his bite. Thinks it must be a devil-fly, and entreated me to kill it — for he saw me cage it — until I pretended to him that it had died long ago. Said he didn’t want his soul to pass into it upon his death. I give him shots of plain water with a hypodermic to keep his morale up. Evidently the fly retains all the properties of the palpalis. Gamba down, too, and repeating all of Batta’s symptoms. I may decide to give him a chance with tryparsamide, for the effect of the fly is proved well enough. I shall let Batta go on, however, for I want a rough idea of how long it takes to finish a case.
Dye experiments coming along finely. An isomeric form of ferrous ferrocyanide, with some admixture of potassium salts, can be dissolved in alcohol and sprayed on the insects with splendid effect. It stains the wings blue without affecting the dark thorax much, and doesn’t wear off when I sprinkle the specimens with water. With this disguise, I think I can use the present tsetse hybrids and avoid bothering with any more experiments. Sharp as he is, Moore couldn’t recognise a blue-winged fly with a half-tsetse thorax. Of course, I keep all this dye business strictly under cover. Nothing must ever connect me with the blue flies later on.
Oct. 9 — Batta is lethargic and has taken to his bed. Have been giving Gamba tryparsamide for two weeks, and fancy he’ll recover.
Oct. 25 — Batta very low, but Gamba nearly well.
Nov. 18 — Batta died yesterday, and a curious thing happened which gave me a real shiver in view of the native legends and Batta’s own fears. When I returned to the laboratory after the death I heard the most singular buzzing and thrashing in cage 12, which contained the fly that bit Batta. The creature seemed frantic, but stopped still when I appeared — lighting on the wire netting and looking at me in the oddest way. It reached its legs through the wires as if it were bewildered. When I came back from dining with Allen, the thing was dead. Evidently it had gone wild and beaten its life out on the sides of the cage.
It certainly is peculiar that this should happen just as Batta died. If any black had seen it, he’d have laid it at once to the absorption of the poor devil’s soul. I shall start my blue-stained hybrids on their way before long now. The hybrid’s rate of killing seems a little ahead of the pure palpalis’ rate, if anything. Batta died three months and eight days after infection — but of course there is always a wide margin of uncertainty. I almost wish I had let Gamba’s case run on.
Dec. 5 — Busy planning how to get my envoys to Moore. I must have them appear to come from some disinterested entomologist who has read his Diptera of Central and Southern Africa and believes he would like to study this “new and unidentifiable species”. There must also be ample assurances that the blue-winged fly is harmless, as proved by the natives’ long experience. Moore will be off his guard, and one of the flies will surely get him sooner or later — though one can’t tell just when.
I’ll have to rely on the letters of New York friends — they still speak of Moore from time to time — to keep me informed of early results, though I dare say the papers will announce his death. Above all, I must shew no interest in his case. I shall mail the flies while on a trip, but must not be recognised when I do it. The best plan will be to take a long vacation in the interior, grow a beard, mail the package at Ukala while passing as a visiting entomologist, and return here after shaving off the beard.
April 12, 1930 — Back in M’gonga after my long trip. Everything has come off finely — with clockwork precision. Have sent the flies to Moore without leaving a trace. Got a Christmas vacation Dec. 15th, and set out at once with the proper stuff. Made a very good mailing container with room to include some germ-tainted crocodile meat as food for the envoys. By the end of February I had beard enough to shape into a close Vandyke.
Shewed up at Ukala March 9th and typed a letter to Moore on the trading-post machine. Signed it “Nevil Wayland-Hall” — supposed to be an entomologist from London. Think I took just the right tone — interest of a brother-scientist, and all that. Was artistically casual in emphasising the “complete harmlessness” of the specimens. Nobody suspected anything. Shaved the beard as soon as I hit the bush, so that there wouldn’t be any uneven tanning by the time I got back here. Dispensed with native bearers except for one small stretch of swamp — I can do wonders with one knapsack, and my sense of direction is good. Lucky I’m used to such travelling. Explained my protracted absence by pleading a touch of fever and some mistakes in direction when going through the bush.