THE NATURALIST'S LIBRARY THE following works of reference, accessible to the American student, are recommended: - General Works and Text-books PARKER and HASWELL, Text-book of Zoöl ogy. CAMBRIDGE Natural History. KINGSLEY, Elements of Comparative DAVENPORT, Introduction to Zoology. Vertebrates HUXLEY, Anatomy of Vertebrated Animals. HUXLEY and HAWKINS, Atlas of Comparative Osteology. Zool-FLOWER, Osteology of Mammalia. CHAUVEAU, Comparative Anatomy of Domesticated Animals. MIVART, Lessons in Elementary Anatomy. AGASSIZ, Methods of Study in Natural His- WIEDERSHEIM, Comparative Anatomy of tory. AGASSIZ and GOULD, Principles of Zoology. Vertebrates. GRAY, Anatomy, Descriptive and Surgical. HUXLEY and MARTIN, Elementary Practi- REIGHARD and JENNINGS, The Cat. OWEN, Comparative Anatomy of Inverte- PARKER and PARKER, Practical Zoology. PACKARD, Zoology. GEGENBAUR, Comparative Anatomy. PARKER, Elementary Biology. KINGSLEY, The Riverside Natural History. CLAUS and SEDGWICK, Text-book of Zoöl ogy. THOMSON, The Study of Animal Life. Embryology BALFOUR, Comparative Embryology. PACKARD, Life Histories of Animals. MARSHALL, Vertebrate Embryology. HERTWIG, Text-book of Embryology: Man and Mammals. KORSCHELT and HEIDER, Invertebrate Embryology. Physiology HUXLEY, Lessons in Elementary Physiology. MARSHALL and HURST, Junior Course in CARPENTER, Comparative Physiology. LANKESTER, Zoological Articles. Practical Zoology. LANG, Comparative Anatomy. SCHMEIL, Introduction to Zoology. Invertebrates HUXLEY, Anatomy of Invertebrated Animals. MACALLISTER, Introduction to Animal MORGAN, Animal Life and Intelligence. Microscopy CARPENTER, The Microscope and its Revelations. GRIFFITHS and HENFREY, The Micro graphic Dictionary. Evolution SCHMIDT, Descent and Darwinism. HAECKEL, History of Creation. DARWIN, Origin of Species. HUXLEY, Lay Sermons, etc. MIVART, Lessons from Nature. The Darwinian Theory. VERRILL and SMITH, Invertebrates of Vineyard Sound. GOULD and BINNEY, Invertebrata of Mas- WOODWARD, Manual of Mollusca. PACKARD, Guide to the Study of Insects. HOWARD, The Insect Book. SMITH, Economic Entomology. DUNCAN, Transformation of Insects. ROMANES, Darwin and after Darwin: I. JORDAN, Manual of the Vertebrates of the Northern United States. ROMANES, The Scientific Evidences of COUES, Key to North American Birds. Organic Evolution. MARSHALL, Lectures on the Darwinian WEISMANN, Essays on Heredity. Special Works CLARK, Mind in Nature. AGASSIZ, Seaside Studies in Natural His tory. TAYLOR, Half-hours at the Seaside. KENT, Manual of the Infusoria. CHAPMAN, Handbook of Birds of Eastern BAIRD, BREWER, and RIDGWAY, Birds of BAIRD, Mammals of North America. ALLEN, Mammalia of Massachusetts. FLOWER and LYDEKKER, Mammals, Living SCAMMON, Marine Mammals of North HARTMANN, Anthropoid Apes. GREENE, Manuals of Sponges and Coelen- PESCHEL, The Races of Man. terata. DANA, Corals and Coral Islands. MARSH, Man and Nature. TYLOR, Primitive Culture. DARWIN, Vegetable Mould and Earth- NICHOLSON, Paleontology. worms. POULTON, The Colors of Animals. Of serial publications, the student should have access to the American Naturalist, Science, American Journal of Science, Popular Science Monthly, Smithsonian Contributions, and Miscellaneous Collections, Bulletins and Proceedings of the various societies, Annals and Magazine of Natural History, and Nature. The following works are recommended as having no English equivalents: APPENDIX THE following directions for experiments are given for the purpose of enabling the teacher and pupil to make further direct observation of the structure and functions of animals, and are supplementary to those given under the head of "Practical Zoölogy." The experiments and dissections are purposely chosen with a view to their simplicity, and to the ease with which they may be performed. Constant reference is made to figures which will both guide and illustrate the dissections. More extended studies may be carried out with the aid of the various works mentioned on pages 483, 484. CHAPTER V The difficulty of distinguishing by ocular observation alone the lower animals from the lower plants may be illustrated by making a microscopic examination of drops of sediment from the bottom of a stagnant ditch. The water will probably be teeming with unicellular organisms, both animal and vegetable, which cannot be differentiated by characters of form, size, color, motion, etc., alone. CHAPTER VII It is especially important that the student become as familiar as possible with protoplasm by a personal study of its structure and physiology. For this purpose the most favorable objects. are the Protozoa, which are readily obtained and easily prepared for examination. Directions are given on page 23. Compare with these the protoplasm seen in the cells of the water plants, as Nitella, Chara (end cells of leaves, and in the colorless rhizoids), and Anacharis; in the stamen hairs of Tradescantia; in Spirogyra; in the cells of the bulb scales of the onion, etc. CHAPTER VIII In studying protoplasm, many kinds of cell will probably be seen. Those mentioned are especially large, and in them the protoplasm is likely to be in quite active motion. To illustrate cell structure use not only the lowest organisms, but also isolated cells from higher animals and plants — for example, blood cells from the frog and from the human body. Frog's blood may be obtained by killing the animal in a box in which has been placed a small wad of cotton saturated with chloroform; as soon as the frog is dead cut into its skin to make the blood flow, then on a glass slide mix a drop of the blood with a drop of a .75 per cent solution of salt in water, put on a cover glass, and examine under a one-fourth to one-sixth inch objective (Figs. 260, 261). Human blood may be obtained by pricking the finger and mounting the drop in the same manner (Fig. 259). Study also the cells seen in a drop of saliva. Some of these, the salivary corpuscles, are small and usually spherical in shape ; others, the epithelium cells, come mainly from the lining membrane of the mouth, are polygonal in outline, have a large nucleus, and are frequently found in groups consisting of several cells. Ciliated cells are easily obtained by placing in a drop of water on a slide a small portion of the gill of a live oyster or clam, and picking it to pieces with dissecting needles (ordinary cambric needles fixed by the eye end into wooden penholders). Examine under a one-fourth or one-fifth inch objective. Some of the pieces will probably be seen swimming about by means of their cilia (Fig. 199, b). With these animal cells compare such vegetable cells as pollen grains, spores of fungi, the cells composing the bodies of some of the fresh-water algæ, etc. As the satisfactory preparation of the tissues requires skill obtained only by long training in manipulation and in the use of hardening fluids, stains, etc., in many cases it will be prefer able to buy prepared specimens. These may be obtained at slight expense from dealers in microscopic supplies. Such specimens, as well as sections of various organs, are very necessary, as it is only by a clear comprehension of the structure of the different tissues and of the organs which they compose that the student can understand the functions of the various parts. CHAPTER XIII The principal chemical changes taking place during digestion in the higher animals may be illustrated with very simple apparatus, and at the cost of but little time. It is not necessary that the student possess any knowledge of chemistry. The object of digestion, viz., the changing of substances which are incapable of absorption into substances which may be absorbed, can be made plain even to the youngest student. The chemicals needed may be obtained of any druggist. The following experiments deal with the three principal digestive fluids, viz., saliva, gastric juice, and pancreatic juice; and with the main kinds of foods, i.e., starchy, albuminous, and fatty substances. SALIVARY DIGESTION (1) The microscopical appearance of undigested starch and its reaction with iodine Into a test tube about one fourth full of water put a pinch of corn starch and shake the tube. Notice that the starch does not dissolve. Examine a drop of the mixture under a microscope and note the starch grains floating about in the water. Add a drop or two of dilute iodine solution to the mixture in the tube and note that it turns a deep blue. Examine a drop of this mixture under the microscope and note that each starch grain has turned blue. Prepare another test tube with water and starch, and boil the mixture in the flame of an alcohol lamp or of a Bunsen burner, keeping the tube agitated all the time in order to prevent the |