Marvels of insect life ; a popular account of structure and habit . boned animals. Insects are often enclosed intight-fitting tin boxes for many hours on collecting expeditions without anyinjury to their health. IMiall and Denny state that though cockroaches incarbonic acid speedily become insensible, yet after twelve hours exposure tOthe pure gas thev survive and appear none the worse. A caterpillar that hasfallen into water soon becomes flaccid and apparently dead through the entry ofwater into the air-tubes, but if rescued and placed where the water can drain out,will revive, and resume its
Marvels of insect life ; a popular account of structure and habit . boned animals. Insects are often enclosed intight-fitting tin boxes for many hours on collecting expeditions without anyinjury to their health. IMiall and Denny state that though cockroaches incarbonic acid speedily become insensible, yet after twelve hours exposure tOthe pure gas thev survive and appear none the worse. A caterpillar that hasfallen into water soon becomes flaccid and apparently dead through the entry ofwater into the air-tubes, but if rescued and placed where the water can drain out,will revive, and resume its former activity. Insects such as bees and wasps, whichexhibit an almost ceaseless activity, are affected by close confinement in restrictedair-space much more speedily than the leisurely flying though larger butterfly or main air-trunk extends along each side of the body, with short branches-connecting wdth each spiracle, and three ramifying branches to each segment of thebody : one to the muscles of the upper side, one to the digestive canal and other ^^. Photo bv] [«• **• How AN Insect Breathes. In this photograph a silkworm has been made transparent to show the ramifications of the system of air-tubes, which are here seenas dark, branching threads. central parts, and the third to the nerves and muscles of the lower side of the The spiracles are sht-Hke openings along the sides, but they are not as simple-as they appear to be from the exterior. In different families there are a variety ofmeans adopted for excluding dust, and valves for closing them when simplest forms are seen in some bugs, flies, and beetles. These have round oreUiptical openings surrounded by a ring of chitin, whilst within is a funnel-likecontraction. In the cockroach the spiracles are permanently open, but there is aninternal valve which can close access to the air-tubes. In the grubs and jiupc-e ofsome flies each spiracle consists of a series of small openings, each with
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecta, booksubjectinsects
