THE PURIFICATION OF THE BLOOD, ETC. 61 



influential. In the higher orders, indeed, frac- 

 tured bones are reconsolidated, divided tendons 

 reunited, severed muscles re -agglutinated ; but 

 here the restorative power ends ; no amputated 

 limb can be recovered. Among several groups 

 of lizards, — and we may instance the geckos,* — 

 the tail, from the character of the articulations, 

 and a strange peculiarity of the fibres of the 

 muscles of the part, is exceedingly brittle, and 

 snaps off with a slight touch. It is, however, 

 soon replaced by a new tail, but a swelling at 

 the base of the reproduced member, like the 

 swelling of the bark around the laceration of a 

 tree, marks the line at which the new growth 

 commenced. The tail of the common vivipa- 

 rous lizard (Zootoca vivipara) of our sunny 

 banks and thickets, is also extremely brittle, 

 and when broken off, is in due time restored. 

 Lobsters and crabs present us with examples 

 of animals capable of reproducing their limbs 

 after forcible removal ; nay, the lobster, when 

 excited by fear or some other impulse, will, by 

 means of a sudden jerk, throw off one of its 

 great claws, and thus for a while lose one of its 

 natural weapons. In a short time a new claw 

 begins to bud, and becomes at length fairly 

 developed, but does not acquire a new covering 

 until the periodical renewal of the whole shell 

 takes place, when the limb, together with the 

 rest of the body, acquires a renovated suit of 

 armour. It is probable that in spiders this 



* See Popular History of Reptiles, Religious Tract Society, 

 p. 126. 



