EEGENERATION OF LOST ORGANS. 119 



the metatarsus the whole portion between that joint and the body will 

 be reproduced of the same dimensions as the corresponding parts on tlie 

 opposite leg ; but the severed metatarsus and the tarsus will reappear much 

 diminished. Precisely corresponding results follow similar excisions of any 

 other joint. 1 



In order to define the time necessary for regeneration of a lost limb 

 Wagner cropped the feet of a number of subjects of different ages. He 

 found that if the foot was amputated a little before the moulting period 

 it was not renewed after the act, but instead a whitish papilla was seen 

 in the stump where the future organ originates. After the next succeeding 

 moult the member appeared small, pale, short, but after the moult irext 

 following that it was thicker and more like the normal. If the leg were 

 amputated immediately after a moult it would be restored during the 

 interval preceding the next moult. 



As a general rule it may be announced that a lost organ is restored in 



a period of time equal to that whicli separates two successive moults at that 



stage in the development of the spider during which the limb is 



Period- iQg^ jf ^i^g fQQ^ (jf ^ spider is removed only two or three days 



i?^ ^ ° after a moult, a new limb is formed in the period which remains 



Regener- '■ 



ation until the following moult. For example, if the leg of Trochosa 



be removed during the period of the second moult, the forma- 

 tion of a new member requires only five days, as that number is just the 

 period which separates the second moult from the third. If the leg be 

 cut away in the period of the sixth moult, a new one is formed in the 

 space of ten days, because between the sixth and seventh moult there is 

 an interval of from ten to twelve days. Thus, if the leg is clipped one 

 or two days after a moult, a new member will ordinarily have time to 

 form before the following moult. 



On the contrary, should a leg or a part thereof be removed at a period, 

 before the moult next to follow, shorter than that naturally required at 

 that stage of development for complete renewal, then the appearance of a 

 new member will be deferred until another moult shall occur ;2 that is 

 to say, two moults must intervene before the lost part is made good. For 

 example, Mr. Wagner cut off the leg of a Trochosa four days after the 

 sixth moult ; the seventh moult took place ten days thereafter, but a new 

 limb was not then formed, and did not appear until the next following 

 moult, viz., the eighth, which occurred eighteen days after the seventh. 

 In such" a case, and all others, the stump of the severed limb, healed and 

 overdosed by its chitinous cicatrix, retains the same appearance until replaced 

 by the new member. 



This process of regeneration will be continued, as often as losses occur, 

 during that period of life when the spider is subject to moult, that is to 



' Blackwall, Brit. Spid., Int., page 8. ^ Blackwall also observed this fact. 



