Huxley was only the surgeon on board the _Rattlesnake_, and his pursuit of natural history was his own affair. There was a special naturalist appointed to the expedition, no doubt chosen because four years earlier, as assistant to Professor Jukes, he had been attached as naturalist to the expedition of the _Fly_ in the same waters. His name was John MacGillivray, and he was the son of an exceedingly able naturalist whose reputation has been overshadowed by the greater names of the middle century. William MacGillivray, the father, sometime professor at the University of Aberdeen, was one of those driven by an almost instinctive desire to the study of nature. In his youth, when he was a poor lad, desiring to see as much as possible of his native land, and above all to visit the great museums and libraries of the south, he walked from Aberdeen to London with no luggage but a copy of Smith's _Flora Britannica_. He was an ardent botanist, a collector of insects and molluscs, and one of the pioneers in the anatomy of birds. There are many curious allusions in his writings which seem to shew that he too was beginning to doubt the fixity of species, and to guess at the struggle for existence and survival of the fittest which the great Darwin was the first to make a part of the knowledge of the world. It must be confessed that his son John, the companion of Huxley, had little of his father's ability. He was three years older than Huxley, and broke off his medical course at the University of Edinburgh to sail in the _Fly_. After the return of the _Rattlesnake_, he was appointed in 1852 as naturalist to H.M.S. _Herald_, then starting under Captain Denham for surveying work round the shores of South America. He left that ship at Sydney, and after many years' wandering about the southern seas, accounts of which he communicated from time to time to Sydney newspapers, he died in 1867. He was a zealous collector of plants and animals, but apparently cared little for the study of his captures, either in life, in relation to their surroundings, like Darwin, or for the structure of their bodies, like Huxley. The somewhat unpleasing nature of his regard for animals appears in the following story which he himself tells: "While at dinner off Darnley Island near the Torres Straits, news was brought that Dzum was under the stern in a canoe, shouting out loudly for Dzoka (MacGillivray's native name), and, on going up I found that he had brought off the barit, which after a deal of trouble I struck a bargain for and obtained. It was a very fine specimen of Cuscus Maculatus, quite tame and kept in a large cage of split bamboo. Dzum seemed very unwilling to part with the animal, and repeatedly enjoined me to take great care of it and feed it well, which to please him I promised to do, although I valued it merely for its skin, and was resolved to kill it for that purpose at my first convenience."