Zoology
2 of the 6 encyclopedias on this shelf carry an entry for Zoology. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
zo-ol'o-ji, the science of animal life. The zoologist is interested in knowing how the parts of an animal's body are made up, what they are used for, how animals manage to live, under what conditions they thrive, how they are distributed, how they produce their kind, and what changes take place with change of circumstances. He is also interested in classifying animals,--setting them off in groups and naming them. There are several subordinate subjects, as ornithology, or the study of birds, entomology, or the study of insects, conchology, or the study of shells, paleontology, or the study of fossils, etc. The first great name among zoologists is Aristotle, the Greek. He described many animals, dividing them into those with blood and those that are bloodless. In the latter class he placed snails, clams, insects, etc. The next great name is that of the Swedish Linnaeus. He introduced a system of arrangement by class, order, genus, species, and variety, a plan still followed. He recognized six classes, mammals, birds, amphibia, fishes, insects, and worms. A Frenchman, Lamarck, distributed the primary classification into vertebrates and invertebrates. Cuvier, also a Frenchman, grouped his classes under four absolute, distinct types,--vertebrates, mollusks, radiates, and articulates. The English Darwin contributed the idea of the origin of species by the influence of changed conditions acting through long periods of time. See also articles on various scientists as HUXLEY; PLINY; LINNAEUS; CUVIER; DARWIN; OWEN; LAMARCK; WALLACE; HAECKEL, and AGASSIZ; and on the principal animals, as the ELEPHANT; SEAL; SHARK; EAGLE; FROG; OYSTER; STARFISH; EARTHWORM; AMOEBA, etc.
Collier's New Encyclopedia (1921)
that portion of natural history which treats of the classification, structure, habits and habitations of animals. Closely related to zoology is the study of embryology, while comparative anatomy and physiology are the branches which dominate the study of the physical structure of man.
What Has Changed in the Last Century
Aiton's 1910 account presents zoology as chiefly classification and description, running from Aristotle's blooded and bloodless animals to Cuvier's four grand types and Linnaeus's six classes; Collier's in 1921 still defines it as "that portion of natural history which treats of the classification, structure, habits and habitations of animals." Darwin's idea of descent with modification, which Aiton's lists as one contribution among many, became the organizing framework of the whole science once it was fused with Mendelian genetics in the modern synthesis of the 1930s and 40s. The tree itself has been rebuilt from DNA: molecular studies from 1997 onward split the invertebrates into groups such as Ecdysozoa, placing insects and crustaceans beside nematodes rather than beside segmented worms, and today around thirty-odd animal phyla are recognized instead of Cuvier's four types. Even the name has receded, with most university zoology departments absorbed into biology or integrative biology, and old subdivisions like conchology surviving mainly as hobbyists' terms.
Written for this edition, 2026.