Can you determine the nursery rhyme being stated below?

Once upon a time there was this ovum consisting of an envelope of albumen, jelly and membranes which decided to moor its entirety on a parapet. Then rather suddenly, and without notice, the ovular succumbed to the Brobdingnagian gravitational pull. The result was that the entire embodiment of the paramount's yeomanry and herbivores were unequal to the task of assemblage.