We shall return later to the pessimism expressed in the last sentence of that quotation from Maeterlink, a pessimism which seems to have caught the popular fancy, but let us first consider some of the rather startling things that make recently been discovered about the biology of that group of animals that make up three-fourths of the animal kingdom even though they are usually not represented in zoological gardens, are the Cinderellas of most zoological museums, and are a part of the great unknown to most university professors of zoology.