This search form searches for the literal phrase you enter. If you enter "rabbit and lion" you do not get the rabbit and lion anecdote but nothing at all as the phrase "rabbit and lion" does not exist.
In case you were wondering why it says lion in the search field, here is the reason. At first the search field was empty and strange enough half the searches were for blank. Apparently lots of people just click without thinking. Now the default searches for something not general (like physics or chemistry, which are easier to find on the contents page), but still gives results. At the moment about 20% of the searches is for lion. It might be mad clickers of it might be people who are wondering what lion results in on a science jokes page.