Asks her to observe whether her dog exposes his teeth when barking and to think of any facts about expression in her birds.
My dear Lucy
I hear that your Dog is a barker: please observe for me whether the (upper) lips are at all retracted or everted when he barks & just before he barks. My impression is that if you open a dog's mouth lips almost hide teeth; but that they are much more exposed, when he barks, which implies some contraction or eversion.
You are so good an observer that I know I can trust your conclusion. The Bark ought not to be a savage one, as that wd give tendency to snarl— a joyful bark or bark of good spirits wd. be best.—
Think of any fact about expression of any emotion in any of your birds.—
Yours affect. | C. Darwin
Our Polly will not bark except as she rushes away to some supposed enemy in forest.