Organism of the Siphonophora. 187 



which is produced by the prolification of daughter-Medusge 

 upon the parent animal, must, by the sprouting forth of a 

 great number of new MeJusee and their dislocated parts upon 

 the body of the primary Medusa, become a stock or cormus, 

 an individual of the fourth order in HaeckeFs sense. The 

 central point of the controversy lay, not in the question be- 

 tween person and animal-stock, but in the issue, prescriptive 

 as to the interpretation of the larva, from the Hydromedusa 

 or from the sxoimming Hydr old- stock. But even in the latter 

 case the Hydromedusa continues to be the sexual animal 

 giving origin to the stock. It is therefore a serious error for 

 Haeckel to assert of this second theory, which we shall desig- 

 nate the Hydroid-theory ^ that it deduces the origination of the 

 latter from the Polypes, and is therefore compelled to conceive 

 of all the swimming-organs of the Siphonophora as tiew for- 

 mations. 



From these considerations, which have already been 

 repeatedly adduced by me, we see how incorrect is the asser- 

 tion that the two theories still stand in direct opposition. 

 Eleven years ago, in a special chapter of my memoir on 

 Halistemma * bearing the title " Ueber die AufFassung der 

 Siphonophoren als polymorphe Thierstocke," I have shown 

 the relation between the two theories, and demonstrated that 

 they are by no means sharply and irreconcilably opposed to 

 each other. In the same way five years afterwards, in a 

 small paper " On the Phylogenetic Development of the 

 Siphonophora " f, I have laid down the position of matters 

 and indicated that even the Hydroid-theory ^ which takes the 

 swimming Hydroid-stock as the starting-point of the com- 

 parison, presupposes as the stem -form the Medusa as the 

 sexual animal from which it originates, and consequently 

 attempted a reconciliation in both directions, with reference 

 both to the conception of polymorphism and animal-stock 

 and to the stem-form of the Medusa. Haeckel has entirely 

 ignored the contents of both these memoirs as regards this 

 question, although, to my surprise, he quotes the former, but 

 does not esteem it necessary even to cite the second in the 

 list of papers appended to his woi'k. Had he taken them 

 into consideration it would certainly have been impossible for 

 him to teach that there at present exists a direct opposition 

 between the poly-person and the poly-organ theory, or to 

 represent his Medusome-theory, which, in reality, coincides 



* " Ueber Halistemma teryestinum &c.," in den Arbeiten des Zool. Inst, 

 zu Wien, torn. i. (1878). 

 t Ibid, torn, V. (1883). 



13* 



