. The Cambridge natural history. Zoology. io6 FEET when extended it is seen that the pressure plate is bent twice at a right angle so as to form a step, the distal part of which runs along the upper face of the basal part of the pad; the apical portion of this latter consists of two large lobes, which in repose, as shown in our Figure (/), fall back on the pad, something in the fashion of the retracted claws of the cat, and conceal the pres- sure-plate. The mode in which Insects are able to walk on smooth perpendicular surfaces has been much discussed, and it appears highly probable that the m
. The Cambridge natural history. Zoology. io6 FEET when extended it is seen that the pressure plate is bent twice at a right angle so as to form a step, the distal part of which runs along the upper face of the basal part of the pad; the apical portion of this latter consists of two large lobes, which in repose, as shown in our Figure (/), fall back on the pad, something in the fashion of the retracted claws of the cat, and conceal the pres- sure-plate. The mode in which Insects are able to walk on smooth perpendicular surfaces has been much discussed, and it appears highly probable that the method by which this is accomplished is the exudation of moisture from the foot; there is still, how- ever, much to be ascertained before the process can be satisfactorily. Fig. 59.—Foot of Pelopaeus, a fossorial wasp: A,tarsus entire; B, terminal joint, upper side ; C, under side. a, claw ; 5, base of pressure-plate ; c, ex- tension - plate ; d, extension- sole ; (!, pad ; /, lobe of pad retracted. comprehended. The theory to the effect that the method is the pressure of the atmosphere acting on the foot when the sole is in perfect apposition with the object walked on, or when a slight vacuum is created between the two, has apparently less to support it. The legs of the young Insect are usually more simple than those of the adult, and in caterpillars they are short appendages, and only imperfectly jointed. If a young larva, with feet, of a beetle, such as Crioceris asparagi be examined, it may be seen that the leg is formed by protuberance of the integument, which becomes divided into parts by simple creases; an observa- tion suggesting that the more highly developed jointed leg is formed in a similar manner. This appears to be really the case. 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 Harmer, S. F.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
