File:The pedigree of man - and other essays (1903) (14762392674).jpg

Identifier: pedigreeofmanoth00haec (find matches)
Title: The pedigree of man : and other essays
Year: 1903 (1900s)
Authors: Haeckel, Ernst Heinrich Philipp August, 1834-1919
Subjects: Man Evolution Man Evolution
Publisher: London : A and H.B. Bonner
Contributing Library: ASC - York University Libraries
Digitizing Sponsor: York University - University of Toronto Libraries

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ody. That white swelling abovethe mouth is a soft mass of nerve-tissue, and is thecentre of the whole soul-apparatus, a brain of thesimplest kind. The fine cords, which radiate from thebrain to all regions of the body, are nerves. We dis-tinguish two different sorts of nerve-fibres. Some arethe organs of the will, motor nerves, or nerves ofmotion. They run from the brain to the muscles,whose fibres, the muscle-fibres, are caused by the motor-nerves to contract. The others, on the contrary, areinstruments of sensation, or sensory nerves. Theycarry the different sense-impressions from the externalskin and the sense-organs to the brain, and thus bringthat organ into relation with the environing externalworld. The sense-organs of so low a worm as this westudy are of course still very simple, but for that veryreason they are deeply interesting. In many wormsthe external integument plays the part of a generalsense-organ, and responds to sensations of different 140 CELL-SOULS AND SOUL-CELLS.
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CELL-SOULS AND SOUL-CELLS. 141 kinds, especially alterations of pressure and changes oftemperature. In other worms are added to this generalsense-organ, the skin, special feelers or tentacles, andin addition eyes of the simplest kind, dark specks inthe skin, enclosing a refracting lens. Ears, also, of thesimplest kind, appear, viz., a pair of depressions orvesicles in the skin, which are lined with minutedelicate hairs; auditory cilia, that are thrown intovibration by sound-waves in a special manner.

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