90 KANSAS UNIVERSITY SCIENCE BULLETIN. 



observer to impose upon her lower order of intelligence by sub- 

 stituting a bogus cocoon of pith. This she will regard with the 

 same marks of tenderness she bestows upon the silken sack 

 freighted with the hopes of her posterity. 



In color the eggs show some variation among the species. 

 The prevailing tints are whitish or yellowish, though shades of 

 red and brown are not uncommon. Even violet tints are 

 ascribed to the eggs of certain species. 



With spiders, as with animals of higher and lower types, the 

 operation of the laws of natural selection begins with the eggs. 

 These become the food of other spiders, or of birds and preda- 

 ceous insects. Thus their numbers are greatly reduced. Out 

 of 600 cocoons of Argiope aurantia, collected by Professor Wilder 

 on one occasion, less than 150 were entire, the others being 

 torn or pierced. Parasitic Hymenoptera of several species also 

 seek out the cocoon, puncture the walls, and lay their eggs there, 

 so that their larvae when hatched may find a supply of food at 

 hand. In the autumn months it is the exception, rather than 

 the rule, to find, in some classes of cocoons, one that is not 

 parasitized. The spider's revenge occasionally comes in the 

 form of a secondary parasite, that, in turn, treats the first in- 

 vader as she had treated the original cocoon builder. 



When the young spiders have hatched their troubles have 

 only begun. In addition to the dangers that threaten the 

 eggs others await them. For example, if we are to accept the 

 doubtful conclusions of some observers, they have to be on the 

 watch lest they fall a prey to the appetites of their larger and 

 stronger brothers. Cannibalism within the cocoon is, however, 

 not an established fact ; more evidence than that already gath- 

 ered is necessary to prove that it exists. 



Field observation reveals the fact that spiders pass the winter 

 in one of three states — in the egg, as already referred to, as 

 newly hatched young in the cocoon, or as half-grown spider- 

 lings and adults in various shelters. Ordinarily, in summer, 

 the eggs hatch in from fifteen to thirty days, the time varying 

 with the species, but when they are laid in the autumn they may 

 not hatch until the following April or May. Of course, only 

 those young which hatch in the warm season and emerge from 

 the cocoon soon after can receive any care from the mother 

 spider. That such broods are cared for with the greatest ten- 



