"Bogart as Duke Mantee gives what is probably his most highly stylized performance. His menacing posture is that of someone who has recently suffered a stroke in the region of the cerebellum. He even speaks oddly -- not his usual snappy lines, but long, drawn-out, ominous, yet resigned to his fate. He seems to agree with Leslie Howard that they are washed up, which is the reason he agrees to kill Howard, who will then leave his money to Betty Davis so she can return to France where she was born."

This is my most favorite move of all-time. I haven't watched it in over 10 years (pre TOS). It was on TV today so I was pleased to watch it - but now post-TOS I noted how the character played by Bogart walked - how he held his arms.... folks, Bogie must have studied someone with TOS! The character even rubs his neck a lot.

See a clip here

If I had TOS, I'd be a surly character too! But back then - they didn't have a dx of TOS... guess that's why they assumed he was portraying someone with a stroke.