The biology of insects / by George H. Carpenter.

  • Carpenter, George H. (George Herbert), 1865-1939.
Date:
1928
Catalogue details

Licence: In copyright

Credit: The biology of insects / by George H. Carpenter. Source: Wellcome Collection.

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    of the eggs, or the young may be fed like the helpless nest¬ lings of birds. Thus family life of a kind is exemplified by many insects, and it is well known how, among the wasps, bees, and ants, for example, the size of the family becomes enormously increased so that the assemblage may not un¬ suitably be compared to a state with its “ officers of sorts,” and the nest to a city whose streets and habitations swarm with orderly and industrious crowds. Such “ social ” insects have from early times aroused the admiration of observant men who have sought to draw, for their own guidance, lessons of wisdom from the apparently intelligent behaviour of these small yet wonderfully organised fellow- creatures. Later we may have opportunity to discuss how far such comparisons between insectan and human societies may justifiably be carried. In bringing to a close our short survey of the field which it is proposed to cover in this volume, a summary—condensed and therefore necessarily technical in mode of expression— of the main features of insect structure in relation to life- conditions may perhaps be of service. Insects, then, are a class of the Arthropoda : segmented appendiculate animals, clothed with a chitinous cuticle which forms an exoskeleton giving attachment to striated muscle-fibres. The head, whose appendages are modified as feelers (one pair) and jaws (usually three pairs), is sharply distinct from the three-segmented thorax which bears six legs and usually four wings, the latter being dorso-lateral outgrowths of mesothorax and metathorax ; thus a variety of precise and rapid motions, including flight, may be possible. The breathing-organs are complex, branching air-tubes, lined with spirally-thickened chitinous cuticle, facilitating direct gaseous exchange between tissues and atmosphere wherewith this tracheal system typically com¬ municates through a series of paired spiracles. The digestive tube has extensive anterior and posterior tracts lined with chitin. The perivisceral and pericardial spaces are haemocoels, the latter receiving blood through its