208 
ANIMAL INTELLIGENCE. 
struction of its cells), but also ramifies into a number of 
diverse directions. Thus we have, in different species, 
wide open networks spread between the branches of bushes, 
&c., closely woven textures in the corners of buildings, 
earth tubes lined with silk, the strong muslin-like snare 
of the Mygale, which, as first noticed by Madame Merian , 1 
and since confirmed by Bates , 2 is able to retain a struggling 
humming-bird while this most beautiful animal in creation 
is being devoured by the most repulsive ; and many other 
varieties might be mentioned. It may at first sight ap- 
pear somewhat remarkable that this instinct of spreading 
snares should on the one hand occur only in one class of 
the animal kingdom, while on the other hand, in the class 
where it does occur, it should attain such extreme perfec- 
tion, and run into so much variety. But we must here 
remember that the development of the instinct obviously 
depends upon the presence of a web-secreting apparatus, 
which is a comparatively rare anatomical feature. In 
caterpillars, which are not predaceous, the web is used only 
for the purposes of protection and locomotion ; and it is 
easy to see that the spreading of snares would here be of 
no use to the animals. But in spiders, of course, the case 
is otherwise. Once granting the power of forming a web, 
and it is evident that there is much potential service to 
which this power may be put with reference to the vora- 
cious habits of the animal ; and therefore it is not to be 
wondered that both the anatomical structures and their 
correlated instincts should attain to extreme perfection in 
sundry lines of development. The origin of the web- 
building structure was probably due to the use of the 
web for purposes of locomotion or of cocoon-spinning, as 
we see it still so used in the same way that it is used by 
caterpillars for descending from heights, and in the case 
of the gossamer spider for travelling immense distances 
through the air. As the anatomical structures in question 
differ very greatly in the case of spiders and in that of 
caterpillars, we may wonder why analogous if not homolo- 
1 Naturalist on the Amazon , p. 83. 
2 For many other confirmations see Sir E. Tennent, Nat. Hist.Ceylan 9 
pp. 468 -69. 
