I. Immediate cause of the infirmities of age not yet well ascertained; must be sought in the laws of animal excitability; debility induced by inactivity of many parts of the system; organs of sense become less excitable; this ascribed to habit; may arise from deficient secretion of sensorial power; all parts of the system not changed as we advance in life. II. Means of preventing old age; warm bath; fishes; cold-blooded amphibious animals; fermented liquors injurious; also want of heat, food, and fresh air; variation of stimuli; volition; activity. III. Theory of the approach of age; surprise: novelty; why contagious diseases affect a person but once; debility; death. NOTE VIII. REPRODUCTION. I. Distinguishes animation from mechanism; solitary and sexual; buds and bulbs; aphises; tenia; volvox; polypus; oyster; eel; hermaphrodites. II. Sexual. III. Inferior vegetables and animals propagate by solitary generation only; next order by both; superior by sexual generation alone. IV. Animals are improved by reproduction; contagious diseases; reproduction a mystery. NOTE IX. STORGE. Pelicans; pigeons; instincts of animals acquired by a previous state, and transmitted by tradition; parental love originates from pleasure. NOTE X. EVE FROM ADAM'S RIB. Mosaic history of Paradise supposed by some to be an allegory; Egyptian philosophers, and others, supposed mankind to have been originally of both sexes united. NOTE XI. HEREDITARY DISEASES. Most affect the offspring of solitary reproduction: grafted trees, strawberries, potatoes; changing seed; intermarriages; hereditary diseases owing to indulgence in fermented liquors; immoderate use of common salt; improvement of progeny; hazardous to marry an heiress. NOTE XII. CHEMICAL THEORY OF ELECTRICITY AND MAGNETISM. I. Attraction and repulsion. II. Two kinds of electric ether; atmospheres of electricity surround all separate bodies; atmospheres of similar kinds repel, of different kinds attract each other strongly; explode on uniting; nonconductors; imperfect conductors; perfect conductors; torpedo, gymnotus, galvanism. III. Effect of metallic points. IV. Accumulation of electric ethers by contact. V. By vicinity; Volta's electrophorus and Rennet's doubler. VI. By heat and by decomposition; the tourmalin; cats; galvanic pile; evaporation of water. VII. The spark from the conductor; electric light; not accounted for by Franklin's theory. VIII. Shock from a coated jar; perhaps an unrestrainable ethereal fluid yet unobserved; electric condensation. IX. Galvanic electricity. X. Two magnetic ethers; analogy between magnetism and electricity; differences between them. XI. Conclusion. NOTE XIII. ANALYSIS OF TASTE.