Elizabeth Cary Agassiz, Louis Agassiz: his life and correspondence, third edition

[229] but that special action which we call organic, in which every part becomes cause or effect, seems to me distinct from the changes which our planet has undergone. I pause here, for I feel that I must annoy you, and I care for you too much to run that risk. Moreover, a superior man like yourself, my dear friend, floats above material things and leaves a margin for philosophic doubt.

Farewell; count on the little of life that remains to me, and on my affectionate devotion. At twenty-six years of age, and possessed of so much knowledge, you are only entering upon life, while I am preparing to depart; leaving this world far different from what I hoped it would be in my youth. I will not forget the Bichir and the Lepidosteus. Remember always that your letters give me the greatest pleasure . . . .

[P. S.] Look carefully at the new number of Poggendorf, in which you will find beautiful discoveries of Ehrenberg (microscopical) on the difference of structure between the brain and the nerves of motion, also upon the crystals forming the silvered portion of the peritoneum of Esox lucius.