56 ECHINODERMATA. 



have been regenerated. We know that these were the second set which 

 had been generated in the sac, the first having separated within a month 

 of the original acquisition of the animal. 



New and most interesting illustrations of the reproductive process 

 advancing in living adult animals, are afforded by the preceding narra- 

 tive. They shew, not merely that a creature of considerable size, and 

 complex organization, may survive the loss of many important parts, 

 whereon exclusively the vital functions might be supposed dependent, 

 and that during a long interval, without perishing, but that these will be 

 regenerated entire. Nay, that a second loss, apparently of equal extent 

 and importance, may ensue, yet leaving us to presume, that it also will 

 be repaired. 



Nevertheless, that such mutilation results from some natural pro- 

 cess or condition incident to the animal, is void of all probability, for it 

 must be rather ascribed to accidental causes, or consequent on something 

 beyond the course of those physiological arrangements regulating the 

 ordinary existence of living beings. Perhaps, like rupture of the sac of 

 the Holothuria pentactes, it follows exposure to a certain degree of con- 

 straint or violence unknown. 



There are certain animals, it is true, which lose and regain impor- 

 tant parts, because those originally developed in their system may be of 

 insufficient strength or permanence to accompany them throughout life ; 

 or, as seen in the larger tribes, they may be lost and regained periodically, 

 the new serving to discharge the functions of the old. Likewise the 

 organs of certain creatures, few in the beginning, multiply continually by 

 new evolution during a long portion, if not the whole of their life. By a 

 singular natural process also, propagation of the race may be carried on 

 simply by a fragment separating from the body of the parent, wherein 

 the organs are for a time latent, and then visibly developed for essential 

 purposes, as well as proving resemblance to the animal when entire. 

 These, and other similar peculiarities, open to the view of the admiring 

 naturalist additional sources of wonder at the arrangements which may 

 affect individual form without affecting life. But that divulsion, rending 

 the very intestines with a great complex organic mass from the body of 



