My excuse is that you yourself had rather vaguely referred to some wound or blood poisoning or operation, on the jaw or the throat.

Not to beat about the bush any more, the idea came into my mind that _if_ in some way the knife or the enemy's bullet had interfered with your thyroid gland--Twig what I mean?
I mean, that if your old man has not been exaggerating and that the difference between the naughty boy whom he sent up to London in--what was it?
1896 ?--and the perfectly behaved, good sort of chap that you are _now_ is no more than what usually happens when young men lose their cubbishness, _why_--_why_--do you take me ?--I ask myself whether the change had come about through some interference with the thyroid gland.

Do you understand?
And I thought, seeing how intensely interesting this research has become, you might have told me more about it.

Just what _did_ happen to you; where you were wounded, who attended to you, what operation was performed on the throat--only the rum thing is there seems to be no scar--well: now _you_ help me out, that is unless you feel more inclined to say, 'What the _hell_ does it matter to _you_ ?'"...
David by this time has grown scarlet with embarrassment and confusion.

But he endeavoured to meet the situation.
"My character _has_ changed during the last five years, and especially so since I came back from South Africa.