OHAPTEE YL 



REGENERATION OF LOST ORGANS AND ANATOMICAL 



NOMENCLATURE. 



I. 



The regeneration of a spider's lost legs and palps is a fact well known, 

 and has been a subject of much observation, experiment, and speculation. 



In brief, it may be said that the action is the result of two 

 Renewal processes, the atrophy of the old tissues and the formation of 

 „ new, which are effected simultaneously and in the same period of 



time. If a spider's leg be severed by accident or amputated, all 



the tissues which fill the stump of the leg gradually disappear, and within 



the cavity so formed a new organ originates and is completely developed. 



Among early writers upon this phenomenon is Dr. Heineken, who 



reached the following conclusions -^ (1) Spiders can not only reject a 



mutilated extreme joint, but reproduce it ; (2) as the period of 



Heine- moulting ceases reproduction ceases also, even from the suture ; 



"(3) tlie power of reproducing the limbs is restricted to certain 



tions. periods of spiders' lives, but as soon as the animal ceases to 



moult its skin, in other words, becomes adult, its limbs cease to 

 be reproduced ; (4) until the growth of the limb was perfected, it appeared 

 to Heineken that between the different moults little increase took place, 

 and the act of moulting two or three times seemed to accomplish the full 

 formation of the limb ; (5) up to the period of the next moult the stump 

 or suture, whichever it might be, remained externally unchanged ; (6) 

 the animal retired into a covering which it had woven for a day or 

 two and then came foi'th with the limb or joint renovated. The above 

 conckisions have been since shown to be substantially correct. 



Some of his inferences, however, are not yet verified, for example, 

 his experiments and observations which seemed to indicate that spiders 

 possess the power of throwing off their joints at will, at least under cer- 

 tain circumstances. A large Lycosa, dropped by him into boiling water, 

 instantly parted with six legs at the sutures. Another Lycosa on being 

 held by one hind leg instantly threw it off. I have met nothing that 

 confirms these statements, and know no similar records ; and do not believe 



• Experiments and Observations on the Casting Off and Reproduction of Legs in Crabs 

 and Spiders by C. Heineken, M. D., Zoological Journal, Vol. I^'., 1828-9, pages 284-294. 



(116) 



