342 350 532 ... 542 ... ... VI.-FUNCTIONS AS RELATED TO THESE STRUCTURES VII.-PSYCHICAL LAWS AS THUS INTERPRETED ON THE ACTIONS OF ANESTHETICS AND NARCOTICS 629 CHAPTER I. THE NERVOUS SYSTEM § 1. The lowest animal and the highest animal present no contrast more striking than that between the small self-mobility of the one and the great self-mobility of the other. A monad passing, apparently with some rapidity, across the field of the microscope, really advances with extreme slowness its velocity, unexaggerated by combined lenses, being about that of the minute-hand of a watch. The parts of a disturbed sea-anemone draw themselves together with a speed which, though immensely greater than that of a monad through the water, is insignificant as measured by the speed of most terrestrial and aerial creatures. Comparing the movements of Protozoa, or of Zoophytes, with those of Birds that keep pace with railway trains or those Mammals that gallop a mile in a minute, their locomotive powers seem scarcely appreciable. Masses being supposed equal, the quantity of motion generated in the last case approaches a million times that generated in the first. Contrasts of this kind exist within each great division of the animal kingdom, as well as in the animal kingdom taken as a whole. The sub-kingdom Annulosa shows us an immense difference between the slow crawling of worms and quick flight of insects. Among Mollusks the sluggishness of the Tunicata is no less marked than the activity of the Cephalopoda. And between the inferior or water |