March saw him back in Charleston, where he attended the annual meeting of the American Association for the Advancement of Science. Then to Washington, where he delivered four lectures at the Smithsonian Institution. At Charleston he again met Agassiz, and once more records the profound impression which the American zoologist produced upon him. "His fine thought," he writes, "of reforming the classifications of animals by a more intimate study of their young in the various stages from embryonic life to full development, grows apace; and if he lives to bring out his conception of a system based upon this, it will not only crown his memory for ever, but be the greatest step of the present age in zoological science... He is certainly a man of extraordinary genius, great energy, and with the most rapid inductive powers I have ever known. I could not help saying to myself, as I sat and listened, Well, it is pleasant to be hearing all this, as it is uttered, and for the first time. If one lives to be an old man, one will have to say, 'I remember to have heard Agassiz say so and so,' and then every one will listen, just as we should do to a person who had conversed with Linnaeus or Cuvier." We must remember that this appreciation of Agassiz's ideas was written nine years before the publication of Darwin's Origin of Species, and at a time when American men of science were much interested in a controversy as to whether mankind are all descended from Adam and Eve, or from several separate creations in different parts of the world. One of his last letters written on American soil contains a note on another subject, significant in the light of subsequent events. "I have been twice at sittings of the Senate, and have heard a good sensible speech on the Union question, which is now agitating folk here... The bone of contention is Slavery."
The spring of 1850 saw him once again settled in Dublin, with a great accumulation of work on hand. Part of the summer was spent in collecting Algae on the coast of Antrim; and he met again his friends Asa Gray and his wife, who were visiting Europe. Another acquaintance made at this time, which ripened into a warm friendship, was the result of the finding by Mrs Alfred Gatty, well-known as a writer of fiction, of the Chrysymenia orcadensis of Harvey at Filey, in fruit for the
