208 



AMERICAN SPIDERS AND THEIR SPINNING WORK. 



f 



But in the case of females who, for whatever reason, have been be- 

 lated in positing their eggs, the frosts of early autumn probably have 

 the effect of retarding the process of development; and when 

 the later autumn frosts and the winter cold follow, the eggs of 

 such cocoons remain unhatched until the first warm days of 

 coming spring quicken their vitality. This is probably true of other spe- 

 cies than Argiope. I have never made any experiments upon the effect 

 of frost to retard or prevent the hatching of spider eggs, but ain inclined 

 to think that cold has this effect upon them, as it is known to have upon 

 the development of insects. 



On May 22d, one exceedingly cold season, I found the young of Epeira 

 sclopetaria, at Atlantic City, all escaped from their cocoons, great num- 

 bers of which were fixed upon the cornices of various buildings around 

 the Inlet wharf. At the same time many cocoons of Epeira triaranca 

 had the young still within them. I have had young Insular spiders 

 colonized upon my vines make their exode May 19th. 



M. Vinson says that July 1st Gasteracantha bour- 

 bonica, a Madagascar species, enclosed in a flagon, had 

 fixed her cocoon against the side. On the 25th the 

 little spiders were hatched. They were perfect as to 

 their forms, but were still imprisoned within the co- 

 FIO. 241. Young Agaiena coon. They presented a blackish appearance. They 

 stripping off the first issued from the cocoon and scattered on the llth of 

 August, a period of seventeen days after hatching. So 

 that under an African winter the hatching of eggs and escape of the 

 young occupies a period of forty days. 



On the disengagement of young spiders from the egg every part is en- 

 closed in a membranous envelope ; they are embarrassed in their move- 

 ments ; are unable to spin or seize prey, and seem indisposed 

 to action. For the unrestrained exercise of these functions it 

 is requisite that they should extricate themselves from the cover- 

 ing which impedes them. This operation, or, as it may be termed, their 

 first moult, occurs after a period whose duration is regulated principally 

 by the temperature and moisture of the atmosphere. The first moult in- 

 variably takes place in the cocoon, or general envelope of the eggs, and 

 the young spiders do not quit the common nest until the weather is 

 mild and genial. 1 



Once, while peeping inside a cocoon of Agaiena nama, I was fortu- 

 nate enough to observe a spiderling in the last stages of this first moult. 

 While it held on to the flossy nest with the two front and third pairs 

 of legs, the hind pair was drawn up and forward, and the feet grasped 

 the upper margin of the sack like shell, which, when first seen, was 



First 

 Moult. 



1 Blackwall, " Spiders of Groat Britain and Ireland," Intro., page 6. 



