76 



in a natural manner, if we regard the rays of the star-fishes not as real antimera, but as 

 morphological individuals of the 5 ,h order, or persons. 



The whole star-fish may be thus properly regarded as a colony (cormus) a collection 

 of articulated persons which have arranged themselves in a radiary form round a com- 

 mon centre, and here formed for themselves a common ingestive aperture, in the same 

 manner as the individuals of the Botryllus colonies arrange themselves radially, and form 

 for themselves a common egestive aperture. But as in the case of other colonially orga- 

 nised animals, we do not define the original form according to the form of the colony itself, 

 but according to the structure of the constituent individual animals or persons, so we come, 

 in the case of the star-fishes, to the result that the fundamental form of these animals is not 

 the radiate form, but the bilateral symmetrical (eudipleural), and that the apparently radiate 

 structure is of secondary origin produced by concrescence of a number of eudipleural per- 

 sons arranged around a common centre. In this manner the last reason would fall away 

 for the union (in itself so unnatural) of the Zoophytes and Echinoderms under one and the 

 same animal type. We might as well consider the star-shaped Botryllus colonies among the 

 Ascidiae as radiate animals; which probably no one at present would think of doing. 



If we accept the above theory (first clearly formulated by Hackel) of the compound 

 structure of the Echinoderms, as properly representing complexes of animals or conhi. it 

 must be admitted that this cormus in the Brisinga is less centralised than in any other 

 Echinoderms; the arms (in this case according to Hackel persons) — as well by their con- 

 siderable size and loose connexion with the insignificant disc, as by their possessing besides 

 the other organic systems, also a perfect apparatus of generation with corresponding geni- 

 tal apertures — exhibiting an independence that is without parallel in any other Echinoderm. 

 In examining a Brisinga it will therefore be much easier to recognise a real colony or 

 complex of animals, than in examining most other Echinoderms, where the already far 

 advanced centralisation of the cormus undeniably makes such recognition in many cases 

 very difficult. The preponderance of the arms over the insignificant disc, is in the Brisinga 

 so great, that the conception hitherto prevailing of the disc in star-fishes as representing 

 the principal part of the body, of which the arms are only radiating expansions, must here 

 be completely reversed; as we must necessarily consider the arms in the Brisinga as the 

 principal parts, to which the disc only stands in the relation of a sort of appendage. It has 

 also been previously stated, that I have been able to convince myself by direct experiments, 

 that the single arms of the Brisinga, detached from the disc, continue to live and to exer- 

 cise their ordinary vital functions, even long after the disc itself has ceased to live ; and 

 that there is likewise a very great probability for their being capable, under favorable cir- 

 cumstances, of continuing their life, each for itself, and little by little reproducing the other 

 parts belonging to a complete colony, the disc as well as the rest; I have even felt bound 

 to state, as something which has the highest degree of probability for it, that such a sue- 



