My legs still refused any sort of strenuous duty.
"The staff surgeon at this station is a man of ideas," he announced as we rounded a big rock and passed down a narrow glade in the jungle.
"He is original.

He is not like some of our official fools.

He studies." I refused to seem curious, and walked beside him in silence.
"He studies sleeping sickness.

If he can find the key to the solution of that scourge it will mean promotion for him.

He has noticed that the sleeping sickness is always at its worst beside the lake, and putting two and two together like a sensible man has reached the conclusion that the disease may be propagated in some way in the blood of these things." We emerged into a clearing in which a pool more than a hundred yards long and nearly as many wide was formed naturally by a hollow in the surface of a great sheet of granite.