- Sherlock Holmes: A dog a reflects family life, Watson.
- Dr. John Watson: [uninterested] Does it, indeed?
- Sherlock Holmes: Whoever heard of a frisky dog in a gloomy home? Or a sad dog in a happy one? Snarling people have snarling dogs.
- Sherlock Holmes: [voiceover as he writes note] Watson. Come at once if convenient.
- [pause]
- Sherlock Holmes: If inconvenient, come all the same.
- Sherlock Holmes: My card.
- Professor Presbury: Two hundred and twenty-one *B*. Hardly an address to inspire confidence.
- Sherlock Holmes: Well, I've never sought to inspire confidence in others; I have quite enough of my own.
- [last lines]
- Dr. Watson: If I may say so, Holmes, I think you went a little too far in allowing Lestrade all the credit.
- Sherlock Holmes: Not all, Watson. You can file it away in our archives. One day the entire truth can be told.
- [first lines]
- Professor Presbury: You may inform the Secretary of the Royal Society that I have entitled my Michaelmas lecture 'Darwin's Fundamental Error'.
- Jack Bennett: That'll raise a few hackles, sir.
- Professor Presbury: Will it not.
- Professor Presbury: My assistant had no authority to engage you in this matter; kindly enquire into it no further. Should you persist, I shall have no hesitation in calling the police. Lestrade of the yard is well known to me, so beware.
- Sherlock Holmes: I would hesitate in calling Lestrade, Professor, if you wish to have the mystery solved.