LIMITATION OF FAMILIES 123 



two or three moults have been gone through, and this usually 

 occupies about a week, the young spiders remain near the cocoon 

 or the mother. Amongst those that spin geometrical webs, 

 the young cling together in a great yellow ball, but if this be 

 disturbed or touched, they suddenly scatter into a golden mist, 

 each little spider shooting out at the end of a long, almost invisible 

 thread of silk, and then when the disturbance is over, they re- 

 assemble. This period of dwelling together in amity does not 

 last long, for as soon as the spiders are able to feed they assume 

 the fierce habits of their race and are ready to fall on each other. 

 At first, however, they settle down near their original home, each 

 making its own web. 



When the young of the wolf -spiders hatch, they soon leave the 

 cocoon. The broods are much smaller in numbers, as the mothers 

 could not drag about a heavy weight, and the young creatures 

 climb on the back of their mother and accompany her on her 

 hunting expeditions. 



Sooner or later, however, spiders have to disperse to avoid the 

 reawakened instincts of their mother and the fierce attentions of 

 their hungry brothers and sisters. Many of them do it by a curious 

 device, making use of the wind like the winged or tufted seeds of 

 plants. On a fair but windy morning they climb up to the highest 

 point available, to the topmost bar of a fence, to the edge of a high 

 wall or to the extreme twigs of bushes. There they raise them- 

 selves on the ends of their legs with the abdomen held erect and 

 pointed backwards away from the wind. Then little tufts of delicate 

 silk are shed out from the spinnerets and float in the breeze until 

 they are long enough and have enough surface to carry the spider 

 from its support. The caprice of the breeze determines the course 

 and distance of the flight, but just as a spider can haul in the thread 

 which binds it to a spot from which it has dropped, so when it is 

 floating it can roll up its sail, piece by piece, until it descends 

 to the ground. 



Insects in every stage of their lives suffer greatly from the 

 inclemency of the weather, the ravages of disease, and the attacks 

 of other insects, of spiders, and especially of frogs, reptiles, birds 

 and mammals, many of which live almost entirely on an insect 

 diet. Some insects are extremely prolific, but none the less, especially 

 in the higher members of the higher groups, the old thriftless method 

 of large broods left to take their chance in the world is replaced by 

 smaller broods for the safety of which great precautions are taken. 



