. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 122 THE NERVOUS SYSTEM [CH. the mouth and oesophagus, and connected with the brain at two points. The first three of these are often classed together as the central nervous system. In the imaginal Dragonfly, the ventral nerve cord apparently contains only ten pairs of ganglia, though in the larva we can count eleven. This is due to the fact that the first abdominal ganglion moves up into the thorax, and fuses with the metathoracic ganglion posteriorly. The ninth and tenth abdominal segments contain no ganglia; but the gang
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 122 THE NERVOUS SYSTEM [CH. the mouth and oesophagus, and connected with the brain at two points. The first three of these are often classed together as the central nervous system. In the imaginal Dragonfly, the ventral nerve cord apparently contains only ten pairs of ganglia, though in the larva we can count eleven. This is due to the fact that the first abdominal ganglion moves up into the thorax, and fuses with the metathoracic ganglion posteriorly. The ninth and tenth abdominal segments contain no ganglia; but the ganglion of the eighth segment is large, and innervates the last three segments. The table on p. 120 shews the details of the Central Nervous System in a convenient vnc Fig. 55. Diagram of brain of Austrolestes leda Selys, constructed from transverse sections ( x 20). a. Dorsal view. B. Ventral view, al antennary lobe; ant antennary nerve; co circumoesophageal commissure; e eye; fc frontal commissure; fg frontal ganglion; ocl lateral ocelli; ocm median ocellus; og optic ganglion; sog suboesopbageal ganglion; V7ic ventral nerve-cord. Original. The Brain (figs. 55, 56, 57). The brain is a large mass of nervous matter situated in the head, above the oesophagus, and extending transversely across the whole space between the compound eyes. Its exact position with regard to the head-skeleton has already been explained. 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 Tillyard, Robin John, 1881-1937. Cambridge [Eng. ] : University Press
Size: 2070px × 1207px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishercambridgeenguniver
