Page:Popular Science Monthly Volume 8.djvu/192
THE POPULAR SCIENCE MONTHLY.
extraordinary power of apparently dying and returning to life again. "I found his pulse sink gradually," wrote Dr. Cheyne, his medical attendant, "so that I could not feel it by the most exact or nice touch. Dr. Raymond could not detect the least motion of the heart, nor Dr. Skrine the least soil of the breath upon the bright mirror held to his mouth. We began to fear that he was actually dead. lie then began to breathe softly." The colonel tried this experiment a number of times during his illness, and was able to render himself insensible at will.
Dr. Brown-Sequard, in a course of lectures before the Boston-Lowell Institute, last winter, illustrated many like remarkable powers of mind in mental and physical disease, by cases which had come under his own observation. From such cases it would seem that the mind is largely dependent on physical conditions for the exercise of its faculties, and that its strength and most remarkable powers, as well as its apparent weakness, are often most clearly shown and recognized by some inequality of action in periods of disturbed and greatly-impaired health.
WE walk along a rocky beach when the tide is out. Twice every twenty-four hours this narrow zone is sea and twice it is land. Its tenants are, as itself, a sort of dividing zone between land and sea. The Algæ in the tide-pools will remind you of Confervæ in the ponds. The littering on the rocks will remind you of snails. The shapeless, gelatinous clumps adhering to rocks or wharf posts will remind you of garden slugs, or naked snails. We will give our attention first to these soft and shapeless chimps.
They will call up no image in the mind until the sea returns, or until you detach one of them, and drop it into a glass of sea-water. You have a Dendronotus, or a Doris, or an Eolis, or an Aplysia.
Out of the shapeless clump comes a form like that of the sing; but the slug in our captive is soon disguised, for along its back, from end to end, rises a fringe of pinkish papilla?. We have an Eolis. What does Eolis do with these papillæ? The last generation of naturalists said, "He breathes with them."
The last generation was too sparing of the knife. We cut through Eolis's back till we reach the stomach, which we find to be a mere expansion of the intestinal tube. This tube extends lengthwise through the body and lies near the dorsal, not the ventral side. It branches, and the branches branch again, and run up into the papillæ which stand out like quills on an angry porcupine. The papillæ are supplementary stomachs.