More tempting still must have been the official invitation received a few months later to a professorship at Lausanne, strengthened as it was by the affectionate entreaties of relations and friends, urging him for the sake of family ties and patriotism to return to the canton where he had passed his earlier years. But he had cast in his lot with the Neuchatelois and was proof against all arguments. He remained faithful to the post he had chosen until he left it, temporarily as he then believed, to come to America. The citizens of his adopted town expressed their appreciation of his loyalty to them in a warm letter of thanks, begging, at the same time, his acceptance of the sum of six thousand francs, payable by installments during three years. The summer of 1837 was a sad one to Agassiz and to his whole family; his father died at Concise, carried off by a fever while still a comparatively young man. The pretty parsonage, to which they were so much attached, passed into other hands, and thenceforward the home of Madame Agassiz was with her children, among whom she divided her time. In 1838 Agassiz founded a lithographic printing establishment in Neuchatel, which was carried on for many years under his direction. Thus far his plates had been lithographed in Munich. Their execution at such a distance involved constant annoyance, and sometimes great waste of time and money, in sending the proofs to and fro for correction. The scheme of establishing a lithographic press, to be in a great degree at his charge, was certainly an imprudent one for a poor man; but Agassiz hoped not only to facilitate his own publications by this means, but also to raise the standard of execution in works of a purely scientific character. Supported partly by his own exertions, partly by the generosity of others, the establishment was almost exclusively dependent upon him for its unceasing activity. He was fortunate in securing for its head M. Hercule Nicolet, a very able lithographic artist, who had had much experience in engraving objects of natural history, and was specially versed in the recently invented art of chromatic lithography. Agassiz was now driving all his steeds abreast. Beside his duties as professor, he was printing at the same time his "Fossil Fishes," his "Fresh-Water Fishes," and his investigations on fossil Echinoderms and Mollusks,--the illustrations for all these various works being under his daily supervision. The execution of these plates, under M. Nicolet's care, was admirable for the period. Professor Arnold Guyot, in his memoir of Agassiz, says of the plates for the "Fresh-Water Fishes": "We wonder at their beauty, and at their perfection of color and outline, when we remember that they were almost the first essays of the newly-invented art of lithochromy, produced at a time when France and Belgium were showering rewards on very inferior work of the kind, as the foremost specimens of progress in the art."