Читать книгу A Text-book of Entomology онлайн

141 страница из 232

“As the fore legs are directed forward and the hind legs backward, while the middle legs are placed obliquely, the reason of the more marked impressions of the latter is evident.

“The highest testimony to the precise exactitude and accuracy of the walking mechanism of insects is furnished by the fact that in most insects, and particularly in those most fleet of foot, which, whether they are running away or chasing their prey, must be able to rely entirely upon their means of locomotion;—the fact, we say, that whether they desire to move slowly or more quickly, the distances of the steps, measured by the length as well as by the cross-direction, hardly differ a hair’s breadth from one another, and this is also the case when the tarsi are cut off and the insects are obliged to run on the points of their heels (tibiæ).

“Thence, inasmuch as the trunk of insects is carried by two legs and by one on each side alternately, it may surely be concluded a priori that when walking it is inclined now to the right and now to the left, and that the track, too, which is left behind by a precise point of the leg, can in no wise be a straight line; and in reality this is not the case.