It was in 1893 that, for the first time in my life, I found myself in possession of five or six months which were not heavily forestalled, and feeling like a boy with a new half crown, I lay about in my mind, as Mr. Bunyan would say, as to what to do with them. “Go and learn your tropics.” said Science. Where on earth am I to go, I wondered, for tropics are tropics wherever found, so I got down an atlas and saw that either South America or West Africa must be my destination, for the Malayan region was too far off and too expensive. Then I got Wallace's Geographical Distribution and after reading that master's article on the Ethiopian region I hardened my heart and closed with West Africa. I did this the more readily because while I knew nothing of the practical condition of it, I knew a good deal both by tradition and report of South East America, and remembered that Yellow Jack was endemic, and that a certain naturalist, my superior physically and mentally, had come very near getting starved to death in the depressing society of an expedition slowly perishing of want and miscellaneous fevers up the Parana.