[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. In October, 1833, Agassiz's marriage to Cecile Braun, the sister of his life-long friend, Alexander Braun, took place. He brought his wife home to a small apartment in Neuchatel, where they began their housekeeping after the simplest fashion, with such economy as their very limited means enforced. Her rare artistic talent, hitherto devoted to her brother's botanical pursuits, now found a new field. Trained to accuracy in drawing objects of Natural History, she had an artist's eye for form and color. Some of the best drawings in the Fossil Fishes and the Fresh-Water Fishes are from her hand. Throughout the summer, notwithstanding the trouble in his eyes, Agassiz had been still pressing on these works. His two artists, Mr. Dinkel and Mr. Weber, the former in Paris, the latter in Neuchatel, were constantly busy on his plates. Although Agassiz was at this time only twenty-six years of age, his correspondence already shows that the interest of scientific men, all over Europe, was attracted to him and to his work. From investigators of note in his own country, from those of France, Italy, and Germany, from England, and even from America, the distant El Dorado of naturalists in those days, came offers of cooperation, accompanied by fossil fishes or by the drawings of rare or unique specimens. He was known in all the museums of Europe as an indefatigable worker and collector, seeking everywhere materials for comparison. Among the letters of this date is one from Charpentier, one of the pioneers of glacial investigation, under whose auspices, two years later, Agassiz began his inquiries into glacial phenomena. He writes him from the neighborhood of Bex, his home in the valley of the Rhone, the classic land of glacial work; but he writes of Agassiz's special subjects, inviting him to come and see such fossils as were to be found in his neighborhood, and to investigate certain phenomena of upheaval and of plutonic action in the same region, little dreaming that the young zoologist was presently to join him in his own chosen field of research. Agassiz now began also to receive pressing invitations from the English naturalists, from Buckland, Lyell, Murchison, and others, to visit England, and examine their wonderful collections of fossil remains. FROM PROFESSOR BUCKLAND TO AGASSIZ. OXFORD, December 25, 1833.