and (Economy of the Araneidea. 235 



are not reproduced, which is usually somewhat modified in size and 

 form by that circumstance. 



At the penultimate moult of male spiders the digital joints of the 

 palpi become very tumid, in much the greater number of species, by 

 a sudden and rapid advance towards development in the sexual or- 

 gans, and should those parts be detached during the interval which 

 elapses between that and the succeeding moult, though the palpi, 

 indicating by their organization that the animal has arrived at ma- 

 turity, may be reproduced, yet the sexual organs are always absent. 

 (See experiments 3, 7, 13, 15-) Adult males of the species Lycosa 

 obscura^ Dysdera Homhergii, and Philodromus dispar hsive been found 

 in a state of liberty with the palpi unequal in .«ize and the smaller 

 one entirely destitute of the sexual organs. 



When the palpi of male spiders, which had been amputated be- 

 fore the penultimate moult, are reproduced, the sexual organs, per- 

 fect in structure, are reproduced also (see experiments 8, 10, 11, 14<); 

 unexceptionable evidence in support of this singular fact is to be 

 found in their reduced dimensions and integrity of form, but it will 

 scarcely be denied that the original germs of those organs must 

 have been removed with the detached palpi. That the function of 

 the sexual organs is not in the least affected by their reproduction 

 there exists the most satisfactory proof. In the last of those expe- 

 riments, having for their object the determination of the seat of the 

 sexual organs in male spiders, recorded in this report, the male Tege- 

 naria civilis, stated to have possessed the right palpus only when in- 

 troduced to the female, is identical with that which was the subject 

 of experiment 8 in the foregoing series ; consequently, its sexual or- 

 gans had been reproduced, yet the fertility of its mate bore ample 

 testimony to the unimpaired efficiency of their generative agency; * 



If experiments 6 and 16 be referred to, it will be seen that the 

 stumps only of mutilated parts are occasionally produced at the fol- 

 lowing moult, and that the entire parts, of a small size, are some- 

 times restored at a subsequent moult. 



Experiment 12 presents an extraordinary case of the stumps of the 

 palpi being produced at two consecutive moults after they had suf- 

 fered mutilation, though several legs of the same spider, mutilated at 

 the same time, were renewed at the next moult after the infliction 

 of the injury. 



The fact, that reproduced legs, immediately antecedent to the 

 process of moulting, are folded in the integument of the undetached 

 portion of the mutilated limbs, is clearly established by experiments 

 17 and 18. 



With some spiders the duration of life does not exceed the brief 

 space of twelve months, whereas it may be safely inferred from ex- 

 periment 4? that Segestria senoculata does not even complete its se- 

 veral changes of integument and arrive at maturity in less than two 

 years. The individual there stated to have had the digital joint of 

 the left palpus detached on the 18th of May 1839 was then about 

 two-thirds grown, and must have been disengaged from the e^^ in 

 the summer of the preceding year, as this species breeds in the 



S2 



