REGENERATION OF LOST ORGANS. 123 
(Fig. 85, ar.) It afterwards increases from one end to the other more 
equally in length than in width, and nineteen or twenty days afterward, 
with a tarentula of middle age, it presents an organ long, almost com- 
pletely formed, gradually diminishing from the base towards the extremity, 
and much twisted. The articulations of this organ are formed successively 
from the base towards the periphera, the second forms after the first, the 
third after the second, etc. Consequently, this process is accomplished 
nearly as that described by Clarapede! for Lycosids in their embryonic 
period. Thus is accomplished successively the isolation of the tissues be- 
tween the base of the joint and its extremity. Pending this; near the base 
of the foot, one readily observes muscular fibres (Fig. 83, pt 1, and Ms.n), and 
on the surface a chitinous membrane (ct.n), a little elongated at the base. 
(Fig. 83, pt 2.) Here one does not notice that the muscles are isolated, or 
anything but chitinous teg- beh pt 
ument (ct.n); the tip of the ° a "¢ 
foot (pt 3) only the chitino- 
genous layer is isolated. 
Sections of this new 
organ at different stages of 
its development show that 
it first originates the ma- 
trix of the papilla ; its cells SERIES SHOWING THE GRADUAL DEVELOPMENT OF THE NEw LIMB 
at its periphera are in im- WITHIN THE OLD Sumer. 
mediate contact with the Fic. 84, Side view, showing onthe retracted matrix, Mt, a small 
blood A ; th papilla, pt, the beginning of the new leg. Fic. 85. A further 
ooa, environing e neo- stage of growth; ar, base of the new organ. Fic. 86. New limb 
formation. In the mean- just before the moult, folded up within the stump. Other let- 
Si ters as above. (After Wagner.) 
time, as the neo- ; 
formation grows, the exterior layer of the matrix is more and 
more feebly colored; at this epoch the superficial part may be 
regarded as chitinous tegument. The tegument is very fine, and 
does not form simultaneously upon all the neoformation, but gradually, its 
growth extending from the base towards the periphera. ‘Thus the neofor- 
mation presents, from the exterior inwardly, first, a chitinous tegument ; 
second, a chitinogenous layer beneath it; third, the matrix. Within the 
latter the hairs originate from elongated trichogenous cells, in no way 
differing from that already described during moulting,? except, of course, 
that no sheath of the old skin appears in the process. 
, The above statements present the general features of the processes from 
which results the regeneration in spiders of a lost organ. Mr. Wagner adds 
the following deductions: 1. The blood corpuscles, under the influence 
of certain conditions, are subject to metamorphosis, the final result of 
which is the formation of a tissue which resembles chitine. 2. The 
Fic. 84. Fig. 85. Fic. 86. 
Order of 
Origin: 
Hairs. 
' Recherches sur l’eyolution des Araignées. *See Chapter V., Fig. 13. 
