218 POPULAR HISTORY OF THE AQUARIU:^, 



Casting Lirnhs. 

 Crustacea are known occasionally to cast or throw off a 

 limb voluntarily; and if they have thus lost a limb^ or it 

 has been accidentally torn off, it can be reproduced. The 

 following account of this curious process is from Mr. Good- 

 sir, in the 'Annals of Natural History/ vol. xiii. p. 67 : — 

 " It has long been known that the animals belonging to 

 this class have the power of reproducing parts of their body 

 which have been accidentally lost. If one of the more dis- 

 tant phalanges of a limb be torn off, the animal has the 

 power of throwing the remaining part of the limb off alto- 

 gether. This separation is found to take place always on 

 one spot only, near the basal extremity of the first phalanx. 

 The author has found that a small glandular-like body exists 

 at this spot in each of the limbs, wliich supplies the germs 

 for future legs. This body completely fills up this cavity 

 of the shell for the extent of about half an inch in length. 

 The microscopic structure of this glandular-like body is 

 very peculiar, consisting of a great number of large nucle- 

 ated cells, which are interspersed throughout a fibro-gela- 

 tinous mass. A single branch of each of the great vessels, 

 accompanied by a branch of nerve, runs through a small 



