Herbert Birdsfoot:

Oh, I Can Only Sing The High Part.
It's The Only Part I Know.
And When I Sing The High Part,
This Is How I Go:
La, La-la-la-la-la-la, La
La, La-la-la-la-la-la.

Ernie:

I Can Only Sing The Middle.
It's The Only Part I Know, I Know.
And When I Sing The Middle Part,
This Is How I Go:
La, La-la-la-la-la-la, La
La, La-la-la-la-la-la.

Bert:

I Can Only Sing The Low Part, Low Part,
It's The Only Part I Know, I Know.
And When I Sing The Low, Low Part,
This Is How I Go.
(That's Beautiful, Bert!)
La, La-la-la-la-la, La-la, La-la,
La, La-la-la-la-la-la.

Sung By All 3 Together:

When We Put Them All Together
I Am Sure You Will Agree, Agree,
The Whole Sounds Better Than The Parts
As You Can Plainly See.
La, La-la-la-la-la, La-la, La-la,
La, La-la-la-la-la-la, La La La La.