"es ee ee - 
ENGINEERING SKILL OF SPIDERS. 227 
by various threads fastened upon the intersecting lines of the maze. From 
a little corner in the upper part of the leaf a similar line, b, was stretched, 
braced by two interior lines of a like character (ce and d), which 
Laby- like the stem cable were also held in place by numerous slighter 
rinthea’s : . 
Cables, Cords extending through the maze. A careful study of these 
main supporting cables, and indeed of all the lines used for 
upholding the leaf, convinced me that, whether or not the spider was con- 
scious of any principles of engineering, she had in her results proved 
herself an admirable engineer. I kept this leaf under observation for 
a number of days of varied weather, and it never lost its poise, or was 
i PAP? ie ay 
Pale eae 7 
Fig, 215. The snare and stay lines of Agalena novia in a honeysuckle vine. 
moved from its place within the labyrinth. It endured well the strain of 
one of the most severe downpours of rain that I ever saw. It thus stood 
the test of actual use as well as careful observation. 
In accounting for such acts as this, one is compelled to suppose the 
exercise of reasoning powers of some kind by the spider. Whether the 
reasoning may have been accomplished by the processes known to man 
and more highly organized animals, or whether the behavior of the spider 
was the result of sensations produced by her delicate sense of touch, and a 
perception of irregularities of weight and tension, which passes human ex- 
perience, one need not stop to discuss. In point of fact, judging these 
