74 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Some females which had been isolated, produced in succession several gen- 

 erations, each in its order being equally fruitful. 1 



Mr. F. Maule Campbell records an example of probable parthenogenesis 

 in the common English house spider. An immature female of Tegenaria 

 guyonii was taken and boxed in May. It moulted twice, and survived 

 during the winter confined within a large glass bottle. Herein she quite 

 domesticated herself, and was fed throughout the winter. In the early part 

 of April she spun the ordinary cocoon of her species, within which she 

 deposited eggs, and about a month thereafter she died. On the 7th of 

 June, Mr. Campbell, observing some movement in the cocoon, separated the 

 sheets enclosing the eggs and found that two spiders had been hatched. 

 Twelve eggs still retained vitality, while the rest were hard and shriveled. 

 The fertility of this spider, after a confinement of eleven months, during 

 which time she twice moulted, can only be explained by one of the follow- 

 ing alternate causes : First, that she was impregnated previous to the cast- 

 ing of the two exuvise in an early, and therefore immature, stage ; second, 

 that parthenogenesis occurs in true spiders. 2 



Mr. Campbell is inclined to believe that the case recorded by him is 

 one of agamic reproduction, inasmuch as he could find no lumen in the 

 exuviae through which impregnation could have taken place. This is jus- 

 tified by the opinion of Bertkau, which expresses the general belief of ara- 

 neologists : this much is certain, that spiders immediately upon or shortly 

 after the final moult become sexually mature. 3 



1 Cuvier, Animal Kingdom, Lond. Ed., Vol. XIII., page 468, supplement. 



' Jour. Linn. Soc. Zool., Vol. XVI., page 538. 



3 "Ueber den Generationsapparat der Araneiden," page 253. 



