53 



traces of accidental mutilation, and that is by reason of the calm and quiet which alwa3'S 

 reign in the great depths of the sea, and which rarely exist iu the literal zone where so 

 many sorts of external perturbations exercise their influence. It is however presumable that 

 also the deep-sea star-fishes possess the same faculty and facility of repairing by regene- 

 ration all sorts of injuries. This appears very evidently, in the Brisinga. That lost arms 

 can be completely reproduced again from the disc, has been already noticed; and likewise 

 that we often find in the same specimens a great number of such small arms simultaneously 

 sprouting forth. In the specimens delineated by Wyville Thomson (1. c.) there are repre- 

 sented no less than 5 such rudimentary arms in one uninterrupted series. Also in the 

 middle of broken arms regeneration takes place in the same manner very easily. I have 

 once observed such a case in the arm of a full grown male specimen where the reproduced 

 part of the arm was evidently and sharply distinguished from the original basal piece. 

 I shall have occasion in a subsequent section to notice a highly remarkable case, where one 

 of the arms in an otherwise normally developed individual was bifurcate at the extremity 

 (see Tab. II, fig. 3). This monstrous formation of the arm owes its origin without doubt to 

 an accidental lesion and consequent regeneration. In this case the reproducing power shows 

 even such a redundance that it has not confined itself to reproducing the lost piece only, but 

 has done it doubly. It is, as already noticed, my conviction that even a single separated 

 arm will be able to reproduce a completely new disc, with the other arms belonging to the 

 same, as has already been stated with great probability with reference to the genus Ophidi- 

 aster and Linckia (see the above cited memoir of Mr. Liitken). 



That the animal, in otherwise normal circumstances, possesses great tenacity of life 

 under external injuries, is undoubted. It is a different question whether the animal would, 

 under circumstances which may be regarded as exercising an injurious influence on all the 

 vital functions, exhibit any unusual tenacity of life. Now the animal must undeniably find 

 itself so situated when brought up from the deep, as is also clearly indicated by the con- 

 vulsive agency whereby all the arms will almost always in this case detach themselves from 

 their connexion with the disc. Nevertheless I have been able to keep such specimens divi- 

 ded into their separate parts, alive even for many days by supplying them with fresh sea- 

 water in sufficiently large vessels. 



I will mention one more apparently important fact in support of my hypothesis 

 above set forth of the uon sexual propagation, namely that the arms always shewed signs 

 of life during a somewhat longer time than the disc itself whence they were detached. The 

 chief seat of vital force seems thus to be rather iu each single arm than in the disc itself, 

 whence again it appears to be matter of inference that it would be more difficult for a 

 disc detached from all its arms to reproduce a single arm, than lor a single detached arm 

 to form both the disc and all the other arms belonging to it. 



