. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. CHAPTER V THE ALIMENTARY AND EXCRETORY SYSTEMS As the alimentary and excretory systems of the Dragonfly are closely related, both morphologically and physiologically, we shall deal with them together, in a single chapter. The Alimentary Canal (fig. 44). In the Dragonfly, as in all insects, the alimentary canal is formed of three main regions. The most an- terior of these {fore-gut) is formed as an invagination of the ectoderm in the region of the mouth. Hejice its epithehum is continuous with the hypodermis around the mout
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. CHAPTER V THE ALIMENTARY AND EXCRETORY SYSTEMS As the alimentary and excretory systems of the Dragonfly are closely related, both morphologically and physiologically, we shall deal with them together, in a single chapter. The Alimentary Canal (fig. 44). In the Dragonfly, as in all insects, the alimentary canal is formed of three main regions. The most an- terior of these {fore-gut) is formed as an invagination of the ectoderm in the region of the mouth. Hejice its epithehum is continuous with the hypodermis around the mouth, and is covered internally by a fine chitinous lining or intima, corresponding and continuous with the cuticle. In hke manner, the most posterior region {hind-gut) is a similar invagination of the ectoderm, and its epithehum is similarly covered by a fine internal chitinous intima. Separating these two regions lies the mid-gut or mesen- teron ("chylific stomach," "ventricu- lus"') formed from the endoderm. In the Dragonfly it is the mid-gut alone which carries on the processes of di- gestive secretion and absorption. The fore-gut simply serves to prepare the food for digestion, while the hind-gut is concerned with the removal of the waste left Fig. 44. Alimentary canal of Aesch- na hrevistyla Ramb. a. Imago (natural size). B. Larva (x 1*). c. Hind-gut of imago (x 3), to shew remnants of rectal gUls {hr'). an anus; 6c buccal cavity; 6r bran- chial basket; cr crop; g gizzard; il ileum; mg mid-gut; mp Mal- pighian tubules; ms oesophagus; pa pre-rectal ampulla; r rectum; sg salivary glands; si short in- testine; i; vestibule. 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
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