New Bacteria

At a certain medical school, there was a class of bacteriology.
It was that students examined their own saliva by microscopes.

When a certain girl student examined her own saliva, she found a big bacteria.
She was surprised. Because she had never looked it on texts or illustrated books.
So, she called her professor, and she said "Professor! I might find the new bacteria. Look this!"

The professor looked it trough the scope. Then he said to her."Well, my dear. This is a sperm."