176 Mr. J.Blackwall o?i certain Phenomena in the 



1847. The spider moulted on the 14th of the same month, when 

 the stumps only of the mutilated limbs were produced. On the 

 7th of the following July it moulted again, at which time the 

 left posterior leg, of small dimensions, but symmetrical in form, 

 was restored ; the right posterior leg was also restored, but the 

 metatarsus and tarsus were disproportionately small. 



13. On the 14th of June 1847 the right posterior leg of an 

 immature female Agelena labyrinthica was amputated near the 

 middle of the metatarsus. The spider cast its integument on 

 the 2nd of the ensuing July, when the mutilated limb was re- 

 produced. The coxa, femur and tibia were equal in size to the 

 corresponding parts of the left posterior leg, but the metatarsus 

 was very small, and the tarsus was extremely diminutive. 



Experiments 2, 3, 4 and 9 serve to establish the fact, that if a 

 leg of an immature Tegenaria civilis be detached at the coxa four 

 or even six times consecutively, it may be reproduced at each 

 succeeding moult the spider undergoes. This frequent renewal 

 of the same part seems to warrant the conclusion that a repro- 

 duction of the limbs of the Araneidea generally, irrespective of 

 mutilation, actually occurs whenever a change of integument 

 takes place ; and this view of the subject, which probably might 

 be extended to numerous subdivisions of the Articulata, derives 

 additional support from evidence supplied by the other experi- 

 ments. 



That the dimensions of reproduced limbs are in inverse ratio to 

 the extent of the injury previously inflicted on the parts is mani- 

 fest from experiments 1, 3, 10 and 12; thus, palpi and legs de- 

 tached at the axillary joint and coxa are usually symmetrical, but 

 diminutive, when reproduced ; while those amputated at the arti- 

 culation of the digital with the radial joint, and near the middle 

 of the tibia or the metatarsus, on being restored are always very 

 much larger and unsymmetrical ; in point of fact, the develop- 

 ment of the new limb depends upon the capacity of the unde- 

 tached portion of the mutilated part ; for if a leg be amputated 

 near the middle of the metatarsus, as was the case in experiments 

 5, 12 and 13, the coxa, femur and tibia will be of the same di- 

 mensions as those joints of the corresponding leg on the opposite 

 side, but the metatarsus and tarsus will be very diminutive; 

 should the excision be made near the anterior extremity of the 

 tibia, as in experiments 6, 7 and 8, then the size of the coxa, 

 femur and genual joint will be normal, but that of the tibia, 

 metatarsus and tarsus will be very abnormal. These curious re- 

 sults plainly demonstrate, that not only reproduced limbs in their 

 totality, but that particular joints also are limited in their dimen- 

 sions by the capacity of the undetached portion of the mutilated 

 part in which they are developed, and that restored legs and 



