Reader's Guide — 11th Edition

Ancillary  ·  Articles
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Chapter LIXZoology

Contents

  1. General Principles
  2. Protective Modifications
  3. Intelligence of Animals
  4. Animals in Captivity
  5. Classification and Divisions
  6. Protozoa
  7. Metazoa
  8. Natural History

At the very outset of his zoological studies the reader will find that the doctors still differ as to the best and most scientifically logical system to be employed in classification. So important is it that the connotation and denotation of every zoological designation should be definite, that Sir Edwin Ray Lankester devotes the title article Zoology (Vol. 28, p. 1022) mainly to a discussion of systems of classification, and besides there is a separate article Zoological Nomenclature (Vol. 28, p. 1021) by P. Chalmers Mitchell, Secretary of the Zoological Society of London, university demonstrator in comparative anatomy and assistant to the Linacre Professor at Oxford, and adviser to the editor in the organization of the whole subject of zoology in the Britannica.

The Britannica articles may be classified in three divisions: dealing with (i) General Principles, (ii) Systematic, (iii) Natural History.

General PrinciplesThe student should read at any rate some of the general articles mentioned in the chapter on Biology; and these will prepare him for the difficult questions involved in the articles Zoology and Zoological Nomenclature. Supplementary to these are the following: Animal (Vol. 2, p. 48), in connection with which should be read the article Protista (Vol. 22, p. 476) where the borderland between the animal and vegetable kingdoms is further discussed, and the very valuable article Protozoa (Vol. 22, p. 479) in which E. A. Minchin, professor of protozoology in the University of London, discusses the minute animal organisms, which in the last decade have proved immensely important in the study of parasitic diseases. In Larval Forms (Vol. 16, p. 224), and Metamorphosis (Vol. 18, p. 221) Prof. Adam Sedgwick, of the Imperial College of Science and Technology in London, discusses the early history of larvae and their change from larval to adult growth. The articles Metamerism (Vol. 18, p. 215), by Sir Edwin Ray Lankester, and Regeneration of Lost Parts (Vol. 23, p. 36), by P. Chalmers Mitchell, discuss the capacity for repeating parts (as in the case of the common earth worm) and for the formation of new parts to take the place of those lost by accident or injury. The article Monster (Vol. 18, p. 740) by Dr. Charles Creighton will be found very suggestive.

Protective ModificationsThe eyes of most of us are shut to the wonders of the animal kingdom. We know by hearsay that the colouring of an animal or insect, brilliant and startling though it often be, is designed by nature for protection by enabling it to assimilate itself to that of its surroundings. But how many of us have taken the trouble to verify this? The articles Colours of Animals, Bionomics (Vol. 6, p. 731), by Prof. Poulton of Oxford, and Mimicry (Vol. 18, p. 495), by R. I. Pocock, superintendent of the Zoological Gardens in London, will suggest to the reader many objects for observation. Especially interesting in the former article is the section on the use of colour for warning and signaling. In connection with these articles, those on Egg (Vol. 9, p. 13) and Feather (Vol. 10, p. 224), by W. P. Pycraft, of the British Museum, may be read, and Nidification (Vol. 19, p. 666), by Prof. Alfred Newton of Cambridge University, and Hans Gadow, Strickland curator and lecturer on zoology in the University of Cambridge; especially those sections concerned with the precautions taken by the birds for protection and concealment. A very fascinating subject is discussed in the articles dealing with the distribution and movements of animal life. These are Zoological Distribution (Vol. 28, p. 1002), by the well-known zoologist Richard Lydekker; Migration (Vol. 18, p. 433), by Hans Gadow; and Plankton (Vol. 21, p. 720), by G. H. Fowler of University College, London. Reference to these articles has already been made in the chapter on Biology. Closely connected with them is the article on Palaeontology (Vol. 20, p. 579), by Prof. H. F. Osborn, Columbia University and American Museum of Natural History, in which the distribution of prehistoric life is discussed; and, as will be seen from the list below, all the principal species now only found in fossil remains are described in separate articles.

Intelligence of AnimalsThe editor succeeded in getting the psychologist, Prof. C. Lloyd Morgan, of the University of Bristol, who has made a specialty of this particular subject, to write extremely illuminating articles on Instinct and on Intelligence in Animals (Vol. 14, pp. 648 and 680). Interesting as throwing a side light on either the instinct or intelligence of birds, is the section on their song in the article Song (Vol. 25, p. 413). It is hardly possible to look through any of these articles, or those on mimicry and colour, above alluded to, without coming across some striking and interesting fact, as for instance, the sudden change from a divine melody to an anxious croak in the utterance of the male nightingale as soon as the brood is hatched. These articles will be read for their great interest by many who do not intend systematically to pursue the subject of Zoology.

Animals in CaptivityThe housing of animals in captivity is discussed in the articles Aquarium (Vol. 2, p. 237), by Professor G. H. Fowler, University College, London; Aviary (Vol. 3, p. 60), by D. Seth-Smith, curator of birds to the Zoological Society of London; and Zoological Gardens (Vol. 28, p. 1018), by P. Chalmers Mitchell. The first two contain some very useful hints for the care of small aquaria and aviaries; and young people who like to have aquaria at home, and are often disappointed by their failure to keep alive some of their specimens, especially larval and other surface-swimming animals, will find one of their difficulties solved. These surface-swimming animals die of exhaustion from their unaided efforts to keep off the bottom, lacking the support given in their surroundings by the natural flow of the water, native tides, and surface currents. The article describes a very simple arrangement by which this motion of the water can be simulated.

Other articles which will be found very interesting are those on Hibernation (Vol. 13, p. 441) and on Incubation and Incubators (Vol. 14, p. 359). In the latter many will be surprised to note that incubators have been in use in Egypt from time immemorial under the name Mamal. In one district of Egypt alone 90,000,000 eggs are annually hatched out in these old time incubators, of which the secret has been handed down, jealously guarded, from father to son. In the article Taxidermy (Vol. 26, p. 464), Montagu Browne, a practical taxidermist, deals with the artistic as well as the technical aspects of the craft.

Classification and DivisionsTurning to the articles of the chief divisions of the animal kingdom, the most useful arrangement will be to enumerate them in their order. As has been already said, zoologists do not yet agree as to the best system of classification; the one which is given in the Britannica is that upon which the very eminent zoologists who have contributed the special articles, agree as being the most suitable. There are two main grades. The Protozoa (Vol. 22, p. 479) contain the animalcules, mainly microscopic. These are the most elementary forms of life and consist of single cells. The other and more important grade is that of the Metazoa, which are built up of many cells.

ProtozoaThe main subdivisions (called phyla) of the Protozoa are: phylum i. Sarcodina (Vol. 24, p. 208); phylum ii. Mastigophora (Vol. 17, p. 873); phylum iii. Sporozoa (Vol. 25, p. 734); phylum iv. Infusoria (Vol. 14, 557).

MetazoaComing next, the Metazoa in their order are, as follows: phylum i. Porifera (see Sponges, Vol. 25, p. 715); phylum ii. Hydromedusae or Hydrozoa (Vol. 14, pp. 135 and 171) which include aquatic animals of the coral kind; phylum iii. Scyphomedusa (Vol. 24, p. 519) which include groups of shell fish; phylum iv. Anthozoa (Vol. 2, p. 97) with the corals; phylum v. Ctenophora (Vol. 7, p. 592) including the jelly fish; phylum vi. Platyelmia (Vol. 21, p. 826) a group of animals in which creeping first became habitual; phylum vii. Nematoidea (see Nematoda, Vol. 19, p. 359) which include certain kinds of worms; phylum viii. Chaetognatha (Vol. 5, p. 789) an isolated class of transparent pelagic organisms; phylum ix. Nemertina (Vol. 19, p. 363) worm families; phylum x. Mollusca (Vol. 2, p. 669) shell-bearing animals.

Phylum xi. Appendiculata (Vol. 2, p. 220) which include the sub-phyla Rotifera (Vol. 23, p. 759), Chaetopoda (Vol. 5, p. 789), and Arthropoda (Vol. 2, p. 673), the sub-phylum which comprises practically the whole insect family. Important articles on animals in this class are: Hexapoda (Vol. 13, p. 418) which include the wasp, beetle, and other families; the Crustacea (Vol. 7, p. 552) which cover a field wide enough to embrace species as different outwardly as lobsters, wood-lice, and minute water fleas; and Arachnida (Vol. 2, p. 287) the spider family. Phylum xii. Echinoderma (Vol. 8, p. 871) with all the sea-urchins and star fish.

Phylum xiii. Vertebrata (Vol. 27, p. 1047) to which man belongs as an order of a sub-class of a class of a sub-phylum. The most important sub-phylum of the Vertebrata is the Craniata (see Vol. 27, p. 1048). The sub-phyla Hemichorda (Vol. 13, p. 257), Urochorda (see Tunicata, Vol. 27, p. 379), and Cephalochorda (see Amphioxus, Vol. 1, p. 886) deal with the lower orders of Vertebrata. The sub-phylum Craniata comprises the following classes: class i. Pisces, see Ichthyology (Vol. 14, p. 243) with the fishes; class ii. Batrachia (Vol. 3, p. 521), with the frog tribe; class iii. Reptilia (see Reptiles, Vol. 23, p. 136); and in close connection with this—class iv. Aves (see Bird, Vol. 3, p. 959, and Ornithology, Vol. 20, p. 299); class v. Mammalia (Vol. 17, p. 520) to which man belongs.

Phylum xiv. Mesozoa (Vol. 18, p. 187) minute parasitic animals intermediate between the Protozoa and the Metazoa. Phylum xv. Polyzoa (Vol. 22, p. 42) aquatic animals forming colonies by budding. Phylum xvi. Acanthocephala (Vol. 1, p. 109) including the parasitic worms. Phylum xvii. Podaxonia (Vol. 28, p. 1023), and phylum xviii. Gastrotricha (Vol. 11, p. 526) minute animals living at the bottom of ponds and marshes.

Natural HistoryThis is an outline of the main division of the animal kingdom in their order as now classified. The subject of zoology is so vast that the student will probably confine himself to one branch of the subject, perhaps to one small fraction of a division, of which he proposes to investigate the complete natural history. As will be seen from the list below, which is classified, the Britannica offers an immense amount of material bearing on the subject. But of course the study of any one sub-class needs a general knowledge of the foundations of zoological science, so that some acquaintance with the principles on which the animal world is classified is indispensable. As in Botany, it will be easy to see from the article on any individual animal to which family it belongs so that the young student can work back from the particular to the general and find out the whole relationship of the subject in which he is interested by reference to the “systematic” article.

LIST OF ARTICLES IN THE ENCYCLOPAEDIA BRITANNICA ON ZOOLOGY (52 articles)
(For biographies of Zoologists, see the end of the chapter on Biology)

Zoology: General

Zoology, Systematic: Invertebrata

Zoology, Systematic: Vertebrata

Zoology, Natural History: Mammals

Zoology, Natural History: Birds

Zoology, Natural History: Reptiles

Zoology, Natural History: Fishes

Zoology, Natural History: Batrachians

Zoology, Natural History: Insects

Zoology, Natural History: Other Invertebrata

Zoology, Palaeontology