Investigating the conditions under which mutations occur … requires studies of mutation frequency under various methods of handling the organisms. As yet, extremely little has been done along this line. That is because, in the past, a mutation was considered a windfall, and the expression “mutation frequency” would have seemed a contradiction in terms. To attempt to study it would have seemed as absurd as to study the conditions affecting the distribution of dollar bills on the sidewalk. You were simply fortunate if you found one. … Of late, however, we may say that certain very exceptional banking houses have been found, in front of which the dollars fall more frequently—in other words, specially mutable genes have been discovered, that are beginning to yield abundant data at the hands of Nilsson-Ehle, Zeleny, Emerson, Anderson and others.

The swelling and towering omnibuses, the huge trucks and wagons and carriages, the impetuous hansoms and the more sobered four-wheelers, the pony-carts, donkey-carts, hand-carts, and bicycles which fearlessly find their way amidst the turmoil, with foot-passengers winding in and out, and covering the sidewalks with their multitude, give the effect of a single monstrous organism, which writhes swiftly along the channel where it had run in the figure of a flood till you were tired of that metaphor. You are now a molecule of that vast organism.