CONTENTS OF VOL. I. XVll 



CHAPTER XIV. 



ORGANIC FUNCTIONS. 



Classification of organic functions — Diflereut classifications for different purposes 

 — Development of functions by differentiation — Their classification on this 

 basis — Vegetative functions chemical, and structural — Cellular tissue — Differen- 

 tiation of tissues — Growth and development antagonistic — Leaves and flowers 

 — Insect metamorphosis — Transformation of energy in development — Forma- 

 tion of organs — Classification of vegetative functions — Animal functions — Four 

 grades of the motor function — Spontaneous motion — Cilia — Motion in response 

 to a stimulus, in plants : in animals without nerves : through nervous agency 

 • — Nervous mechanism — Two sets of nerves — Reflex action — Reflex action in 

 heart, lungs, and stomach — Reflex actions performed abnormally — Consensual 

 action — Cause of sensation unknown — Voluntary action : depending on nervous 

 stimulus — Instinct — Summary — Sensory functions — Mind — Tabular summary 

 — Development of functions by differentiation. 



Note A : — Only vegetables decompose carbonic acid — All organisms produce it^ 

 Only the green parts of vegetables decompose it, and only in the light — 

 Vegetable tribes that do not decompose cai'bonic acid — No absolute distinction 

 between vegetables and anim als. 



Note B : Formative and Motor Functions : — Actions in Foraminifera at once 

 formative and motor Pp. 154 — 1G6 



CHAPTER XV. 



THE LAWS OF HA31T. 



Meaning of the word habit — Conscious actions becoming habitual — Unconscious 

 instinct of the bee — Motor habits of climbing plants — Motor and mental habits 

 — Formative habits — Virginian creeper — All vital actions become habitual, tend- 

 ing to repeat themselves — Apparent inorganic habits fundamentally different — 

 Theory that organic habits depend on structure, contradicted by embryology — 

 Habits become hereditary — Habit is mysterious — Inherited characters appear 

 sometimes at the same age as in the parent, sometimes earlier — Hereditary 

 tendency without special habit — Habit is changeable, and spontaneously vari- 

 able — I believe in no limit to variation — Habits of varying — Instance of ac- 

 quiring languages — Habits are weakened and destroyed by disuse — Strength of 

 a habit depends on time during which it has been exercised, and on time since 

 it has been exercised — Present strength of a habit — Tenacity of a habit — Here- 

 ditary characters are the most tenacious — Weakening of habits by disuse is a 

 case of the general law — All actions become habitual : all habits become here- 

 ditary : all habits are variable — Reappearance of old habits — Latent habits — 

 Reversion to ancestral characters — Laws of habit are elementary and universal 

 laws of life — Active habits strengthen, passive impressions weaken, by repeti- 

 VOL. I. b 



