CHAPTER Y. 

 MOULTING HABITS OF SPIDERS. 



I. 



Young spiders usually make the ^rst moult within the cradle where 

 the eggs have been laid. The 3'oung of Lycosa and Trochosa remain in 



the cocoon until the second moult, after which they emerge and 

 ou mg gjt^jjj^jgj. ^xpon the mother's back, where the third and fourth 



moults occur before the little fellows begin independent house- 

 keeping in miniature burrows of their own. Wagner asserts^ that the 

 mother softens and partly tears the cocoon at its selvage, thus aiding the 

 exit, and that without such help the little ones fail to escape, and die ; a 

 statement which I feel .sure must be modified. Young Attoids, having 

 undergone the moult, shift their positions to the opposite end of the 

 cocoon, and then moult a second and even third time before egress ; as is 

 shown by the fact that one finds within the same cocoon three separate 

 heaps of skins cast at different ages. 



The subject of cannibalism within the cocoon has already been consid- 

 ered, ^ with the general conclusion that it is rare among spiderlings, but 



sometimes occurs. The Trochosas observed by Wagner would 

 , ^,^°^" appear to be among the exceptions; for not only does the mother 



in captivity devour her broodlings, but the latter feed upon one 

 another, a fact which is closely related to differences developed at the 

 moulting period. At the end of two or three months a considerable differ- 

 ence in size appears among the young of the same brood ; some are more 

 vigorous and agile, others feeble, and those weaklings commonly fall a 

 prey to their stronger fellows. 



The cause of this inequality is traced to the fact that the eggs do not 

 all hatch at one time, and that a whole day or more may intervene 

 between the hatching of one division and another. In general, one remarks 

 in a cocoon, at the second moulting period, one group whose individuals 

 lack two or three days of the time, others on the eve thereof, and still 

 others in the act of moulting. This circumstance alone will explain why, 

 after two moults, the stronger spiderlings are able to overcome and eat 

 the feebler ones. It would thus seem that only the more vigorous enter 

 upon independent lifej while the feebler or those which come more tardily 

 from the egg contribute to the perpetuation of the species by yielding 



> La Mue, page 344. = Vol. II., page 209. 



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