al selection, 167.

Nerve-fibre cell, 70.

Nervous energy, 42, 44.

---- system, 41.

New biological problems, 15.

Nucleolus, 65, 92, 94.

Nucleus, 65, 84, 87, 93, 101, 103, 113, 124, 149;
formation of new, 101.

---- function of, 89, 90, 95.

---- presence of, 87, 88, 89.

---- structure of, 91.

O.

Organic chemistry, 78.

Organic compounds, artificial manufacture of, 78, 82.

Origin of cell machine, 178, 179, 180.

Origin of life, 81, 182.

Osmosis, 29.

Oxidation, 80, 176.

---- as a vital process, 39, 56.

P.

Philosophical biology, 4.

Physical basis of life, 75.

Polar cells, 107.

Potato, section of cells, 67.

Properties of chemical compounds, 79.

Protoplasm, 14, 74, 82, 83, 84, 114, 115, 179.

---- artificial manufacture of, 82.

---- as a machine, 86, 178.

---- discovery of, 74.

---- nature of, 76.

---- structure of, 86, 87.

Purpose _vs._ cause, 11, 12.

R.

Reaction against the cell doctrine, 117.

Reign of law, 4.

---- of the nucleus, 91.

---- of protoplasm, 81, 85.

Relationship, significance of, 143.

Removal of waste, 39, 40.

Reproduction, 54, 80, 124, 148, 176;
--rapidity of, 149.

Respiration, 37.

Reticulum of cell, 87;
--of nucleus, 92.

Root tip, section of, 66.

S.

Schultze, 74, 75.

Schwann, 61, 62, 72.

Secretion, 39, 40.

Segmentation nucleus, 110.

Sensations, 46.

Separation of chromosomes, 100.

Sexual reproduction, 102.

Spermatozoan, 107, 109, 154.

Splitting of chromosomes, 99.

Spindle fibres, 101.

Struggle for existence, 168.

Summary of Part I, 128.

---- general, 182.

U.

Undifferentiated protoplasm, 83.

Unicellular animals, 71.

Units of vital activity, 53.

Use and disuse, 171, 172.

V.

Variation, 148, 157, 160, 176.

Variation from sexual union, 162.

Variation in germ plasm, 161.

Vegetative functions, 41.

Villi, 31.

Vital force, vitality, 13, 15, 34, 37, 52, 80, 85.

Vital properties, 54;
--located in cells, 123.

W.

Wing compared with arm, 144.

Wood cells, 68.

THE END.

==THE LIBRARY OF USEFUL STORIES.==

Illustrated. 16mo. Cloth, 35 cents net per volume; postage, 4 cents per
volume additional.

The Story of a Grain of Wheat. By W.C. EDGAR.
The Story of Alchemy. By M.M. PATTISON MUIR.
The Story of Animal Life. By B. LINDSAY.
The Story of the Art of Music. By F.J. CROWEST.
The Story of the Art of Building. By P.L. WA