88 KANSAS UNIVERSITY SCIENCE BULLETIN, 



it after the eggs are enclosed. Some species die shortly after 

 they lay their eggs, leaving the latter to the vicissitudes of fate. 

 This is especially true of those that mature in the fall, as do the 

 majority of the orb-weavers ; other species, particularly of the 

 jumping spiders, stand guard over their treasures until the 

 young emerge ; while still others carry the cocoon about with 

 them, clasped in their pedipalps or attached to the spinnerets. 

 The least observing student of nature has no doubt quite often 

 seen instances of this latter habit in the spring or early summer, 

 when one may find the running spiders with their cocoons in the 

 grass or under stones. A little later the young emerge and 

 climb upon the mother's back, where they cling for a week or 

 so, until they can shift for themselves. 



The sites chosen for a fixed cocoon seem also to have some 

 reference to the mother's future intent. Cocoons that are to be 

 the objects of her watchful care are usually placed near the 

 spot she has chosen as an abiding-place — in the snare, if she 

 makes one, in the burrow or dwelling-tube, or in an incubation 

 cell made expressly for the purpose. On the other hand, spe- 

 cies that do not survive cocooning will go some distance to find 

 a secluded spot under stones or bark, or in a rolled leaf. The 

 protection of the cocoon in such cases, or occasionally even 

 when guarded, involves the use of various extraneous cover- 

 ings. Sometimes bits of dead leaves or sticks are employed ; 

 at other times fragments of captured insects, like trophies of 

 victory, serve the double purpose of adorning and hiding the 

 cocoon. Often fine earth or, still better, a mortar of clay com- 

 pletely hides the silken sack. Cocoons of this sort, as well as 

 some others, are frequently suspended by a slender pedicle from 

 a convenient support. 



The parts of a cocoon seem to require separate mention. 

 There are two types of outer envelope — one consisting of an 

 entire, homogeneous piece, and one made up of two valves 

 united at a more or less circular suture. This suture may be 

 scarcely noticeable, or it may be a plainly marked zone of 

 weaker tissue that stretches to make room for the young brood, 

 and finally ruptures to permit the egress of the spiderlings. 

 The method of manufacturing such an egg-sack is simple. A 

 circular silken sheet of the proper size is woven, and upon this 

 the eggs are laid. Another similar sheet is then spun over the 



