The Microbe is so very small
You cannot make him out at all,
But many sanguine people hope
To see him through a microscope.
His jointed tongue that lies beneath
A hundred curious rows of teeth;
His seven tufted tails with lots
Of lovely pink and purple spots,
On each of which a pattern stands,
Composed of forty separate bands;
His eyebrows of a tender green;
All these have never yet been seen--
But Scientists, who ought to know,
Assure us that they must be so....
Oh! let us never, never doubt
What nobody is sure about!

Hilaire Belloc

http://www.poemhunter.com/poem/the-microbe-2/