XVI CONTENTS OF VOL. I. 



CHAPTER XII. 



THE DIKECTION OF DEVELOPMENT. 



Highest development is greatest complexity, and greatest distinctness of dissi- 

 milar parts^ Physiological division of labour — Never quite complete — Combined 

 action of parts is most perfect in the highest organisms — Physiological central- 

 ization, or combination — Special perfection in an organ is incompatible with 

 general adaptability— Efficiency of each and all members increaesd by division 

 of labour and combination — Definiteness, a result of division of labour — Leaves 

 and flowers— Worms, millepedes, and insects — Summary — Separation of in- 

 ternal and external parts, universal — External parts protective — Separation of 

 nutritive and reproductive organs, not universal, and not fundamental — Sepa- 

 ration of cellular and vascular structures — Cells unite to form vessels— Sepa- 

 ration, in animals, of nutritive and nervo -muscular systems— Nerves are to 

 muscles what vessels are to nutritive system — Internuncial function of nerves — 

 Helmholtz's experiment — Velocity of nervous stimulus measured— Nerves, 

 probably, transmit energy — Each muscle usually transforms energy for itself — 

 Hydrozoa and bryozoa — Development of vessels out of cells — Resemblance of 

 nervous fibre to muscular — Blood-vessels aud nerves ramify — The heart and the 

 brain — Amphioxus — Blood-vessels and nerves are abundant in the same places 

 — Their action is heightened together — Inflammation — Sleep — Want of fresh 

 blood causes insensibility — Connexion of heart with brain — Dependence of 

 nervous action on circulation not recij)rocal — Opposite relations of blood and 

 nerve to muscle — Blood supplies energy as well as matter — Summary — Ganglia 

 — Sensation. 



Note : The Functions of the Nervous System : — Lewes's theory of sensation dis- 

 proved—Impossible to say where sensation begins — Nerve-fibre may act without 

 ganglionic influence Pp. 132 — 114 



CHAPTER XIII. 



ORGANIC SUBORBINATION. 



Organic differentiation and integration, dependence and subordination — Space 

 and time are conditions of all things — Consequently mathematics is the ground 

 of physical science — Dynamics the basis of physical science — Secondary dyna- 

 mical sciences— Chemistry — Biology — Series of sciences each dependent on the 

 preceding— Dependence not reciprocal — Dependence is not only of the sciences, 

 but of the things — Accidental connexion of histology with ojjtics — Obligation 

 to Comte — Dependence of vital laws one on the other — Vegetative, animal, and 

 mental life— Sleep— Experiment — The series continued— Subortlination of or- 

 ganic functions — Matter subordinate to life — Unconscious life subordinate to 

 mind — Muscular action essentially unconscious — Instance in reverie — Summary 

 — Dependence necessary : subordination not so Pp.145 — 153 



