. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 110 THE ALIMENTARY AND EXCRETORY SYSTEMS [CH. be borne in mind that the normal state (a) represents a state of fasting. This is broken at irregular intervals by large and rapid meals, when the larva is fortunate enough to secure a victim. The larva can fast for long intervals without any danger of starvation^. In fact, as will presently be seen, the longer the larva fasts, the bigger becomes its capacity for deahng with the next meal when it does Fig. 49. Part of epithelium of mid-gut in larva of .-I esc/i/ia s
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 110 THE ALIMENTARY AND EXCRETORY SYSTEMS [CH. be borne in mind that the normal state (a) represents a state of fasting. This is broken at irregular intervals by large and rapid meals, when the larva is fortunate enough to secure a victim. The larva can fast for long intervals without any danger of starvation^. In fact, as will presently be seen, the longer the larva fasts, the bigger becomes its capacity for deahng with the next meal when it does Fig. 49. Part of epithelium of mid-gut in larva of .-I esc/i/ia sp. ( X 330). a. During period of rest. b. During period of preparation, c. During period of activity. bm basement membrane; balls of secretion; cm circular muscle; ib internal lamina of epithelium; Im longitudinal muscle; ns nests of developing cells; nu nucleus of epithelial cell; pm peritrophic membrane; yp yellow pigment granules. After Voinov. We may divide the process of digestion into three periods, (i) the normal period, or period of rest, (ii) the period of preparation, and (iii) the period of activity. (i) The 'period of rest. Fig. 49 a shews the appearance of the cells of the mid-gut, after the completion of digestion of a heavy meal. We have already described this state. We shall only add that, here and there, just within the basement membnme, there 1 I have kept larvae of Synthemis alive for three months without 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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