I have devoted my whole life to the study of Nature, and yet...

I have devoted my whole life to the study of Nature, and yet a single sentence may express all that I have done. I have shown that there is a correspondence between the succession of Fishes in geological times and the different stages of their growth in the egg,-this is all. It chanced to be a result that was found to apply to other groups and has led to other conclusions of a like nature.