REGENERATION 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 the 
opposite leg; but the severed metatarsus and the tarsus will reappear much 
diminished. Precisely corresponding results follow similar excisions'of any 
other joint.) 
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 next 
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 which separates two successive moults at that 
stage in the development of the spider during which the limb is 
Period- Jost, If the foot of a spider is removed only two or three days 
me of  aftersa moult, a new limb is formed in the period which remains 
egener- s : 5 
Sian. 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;? 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. 
such a case, and all others, the stump, of the severed limb, healed and 
overclosed 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 
1 Blackwall, Brit. Spid., Int., page 8. 2 Blackwall also observed this fact. 
