Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . ystem, which has the power of receivingimpressions, and of exciting the most distant parts of thebody to act in accordance with them. 275. Those animals which in-habit bivalve shells exhibit thepowers of respiration, sensation,and voluntary motion, and pos-sess a corresponding develop-ment of the nervous system. Inthe nervous system of the peclenor scallop-shell, {fig. 43,) there isa large ganglion at B
Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . ystem, which has the power of receivingimpressions, and of exciting the most distant parts of thebody to act in accordance with them. 275. Those animals which in-habit bivalve shells exhibit thepowers of respiration, sensation,and voluntary motion, and pos-sess a corresponding develop-ment of the nervous system. Inthe nervous system of the peclenor scallop-shell, {fig. 43,) there isa large ganglion at B, which dis-tributes branches to the gills andmouth, and regulates the re-f>v. system of peo- spiratory movements. Another ten.—A, A, ganglia of the head; B, ^„^„t„ „ • , t ? ?, ?, respiratory ganglion; c, ganglion of ganglion, c, is connected with the the foot; „ esophagus. ^^ ^^ ^ ^ ^.^ ^ animal crawls, and which is called its foot. Near the sidesof the oesophagus, e, are situated two other ganglia, A, A,the nerves of which are distributed to the sensitive ten-tacula which guard the mouth. These two cephalic Describe the nervous system of the THE NERVOUS SYSTEM. 123 ganglia, or ganglia of the head, evidently correspond tothe brain of higher animals, being the instruments of sen-sation and voluntary power, and they exert a controllingdirection over the movements of the animal; while thepedal and bronchial ganglia (those of the foot and ofrespiration) minister to the reflex actions of the organssupplied by them. 276. In animals of higher orders, the ganglia are morenumerous as the variety of functions to be performedbecomes greater; and in proportion as we ascend the scale,the cephalic ganglia become more and more developed,and more and more elevated above the oesophagus, untilthey finally meet on the central line above it, and, in themore perfect animals, take their place in the top of thehead—overlooking, as it were, all the other organ
Size: 1454px × 1719px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectphysiologicalprocess
