. Comparative physiology of the brain and comparative psychology. Brain; Psychology, Comparative. 98 COMPARATIVE PHYSIOLOGY OF THE BRAIN In Vertebrates the head contains special sense- organs, mouth-organs, which are lacking in the other segments. In judging of the relation of the brain- ganglia to the other segmental ganglia of the body this fact should not be overlooked. Not infrequently physiologists have ascribed to a ganglion what in reality was due to the higher differentiation of the peripheral organs of the segment. We desire now to touch briefly upon the behaviour of the muscles after
. Comparative physiology of the brain and comparative psychology. Brain; Psychology, Comparative. 98 COMPARATIVE PHYSIOLOGY OF THE BRAIN In Vertebrates the head contains special sense- organs, mouth-organs, which are lacking in the other segments. In judging of the relation of the brain- ganglia to the other segmental ganglia of the body this fact should not be overlooked. Not infrequently physiologists have ascribed to a ganglion what in reality was due to the higher differentiation of the peripheral organs of the segment. We desire now to touch briefly upon the behaviour of the muscles after extirpation of the ganglion, for the phe- nomena will occupy our attention repeatedly. In the case of loss or a congenital lack of a piece of the spinal cord, the skeletal muscles belonging to the corresponding segment atrophy. Nothing of the kind occurs in leeches or earthworms from whose ventral chain a piece has been removed. I believe that the dif- ference is determined as follows : In worms direct impulses flow from the neighbouring muscles to the muscles that have been deprived of their ganglion, while in Vertebrates, as soon as the spinal cord is destroyed, the protoplasmic connection between the skeletal muscles and the rest of the body is destroyed. FIG. 30. HEAD OF NEREIS. Quatrefages.) (After. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Loeb, Jacques, 1859-1924. New York, G. P. Putman's Sons; [etc. , etc. ]
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