TY - JOUR
AU - IMMS, A. D.
AB - MUCH has been written relative to the morphology of the insect thorax and its appendages, but few of the contributions of recent years have led to any modification of tho present-day conceptions of that subject. The whole problem, however, has been re-invostigated in a comprehensive memoir by Dr. K. E. Siiodsrass,1 whose work is characterised by clarity of deduction and an honest attempt to place the subject on a bettor foundation. In discussing the general problem of segmentation, he takes us back to the primitive soft-bodied ancestors of tho arthropods and points out that in sucb animals the grooves limiting the body-segments coincided with the lines of attachments of tho longitudinal muscles. This same condition is still met with in many insect larvæ. Adult arthropods, oil the other hand, with their hard exoskeletal body-plates, have acquired a secondary segmentation. This has been achieved by the development of a membranous unchitiiiised zone just in front of each muscle-bearing intersegmental groove. The function of this flexible area is to admit of freedom of movement and telescoping of the hardened resistent segments. Such membranous areas are commonly regarded as truly intersegmental in position, but, as Janet was the first to demonstrate, the term intorsegmeiital membrane, although justified from its function, is morphologically inexact. Flexibility could not well be at tho original intersegmental grooves because the muscles are here attached and demand firm support. The dorsal and ventral regions of these grooves have become converted into internal ridges, which have become fused with the skeletal plates immediately behind them as is shown in the accompanying illustration (Fig. 1).
TI - The Morphology of the Insect Thorax
JF - Nature
DO - 10.1038/120460a0
DA - 1927-09-24
UR - https://www.deepdyve.com/lp/springer-journals/the-morphology-of-the-insect-thorax-0q0YsO4yYA
SP - 460
EP - 461
VL - 120
IS - 3021
DP - DeepDyve
ER -