NEAR RELATIVES OF INSECTS. 245 



body becomes darker in color. In the case of spiders 

 which develop slowly all winter, perhaps hatching 

 prematurely, when the natural food does not offer, the 

 young spiders are liable to eat each other. Indeed, in the 

 summer time, if the brood hatching from one clutch is 

 very large, the stronger ones in the sack hatching first 

 eat the weaker; thus gradually thinning out the colony, 

 and bringing about the survival of only the strongest 

 spiders. 



Before the second moult, the young spiders generally 

 leave the cocoon or nest, and for a time live in a web which 

 they spin together. This second moult occurs very soon 

 after hatching and usually is not preceded by any eating 

 on the part of the spiders ; this early abstinence from food 

 is not an anomalous condition. It is duplicated in' the 

 life of the young of many animals, such as chickens, ducks, 

 and birds of many sorts, and even of some of the mammals. 

 Subsequent moults bring the young spiders to adult form, 

 size, and ferocity; and, because of this last fact, the separa- 

 tion of the brood into distinct places of habitation will 

 have taken place before this period is reached. 



Females of the family of running spiders keep their 

 egg sacks with them attached to their spinnerets by the 

 threads reaching from the spinnerets to the mouth of the 

 egg sack. Another spider in the same family carries her 

 egg sack about with her in her hunting expeditions, until 

 the eggs begin to hatch ; then she fastens the sack to some 

 bush or other stem by a loose, irregular web of her own 

 weaving. This web also serves the other valuable purpose 

 of providing the young spiders with a chance meal of 

 insects now and then. So far as known, this is the only 

 instance among the spiders of care for the young beyond 

 the egg stage. 



