In 1959, shortly before his untimely death, Dr. Walker van Riper sent me the head of a broad-tailed hummingbird (Selasphorus platycercus). We had been corresponding about the sense of smell in birds, and he wrote me about his observations on wild birds of this species in Colorado. He designed an ingenious set of experiments in which he fed a population of S. platycercus from specially designed bottles in which the syrup was either pure, contaminated with various tastes, or masked by strong odors. The experiment is described and the data are presented in The Scientific American under "The Amateur Scientist." 1 It is a well-written and well-illustrated paper, but, unfortunately, the title and author are not sufficiently emphasized to get into the indices of the appropriate branches of science. After observing some 700 visits to the feeders, he concluded that the responses of this hummingbird in its search for food