Organism of the Siphonophora. 187 
which is produced by the prolification of daughter-Medusz 
upon the parent animal, must, by the sprouting forth of a 
great number of new Medusz and their dislocated parts upon 
the body of the primary Medusa, become a stock or cormus, 
an individual of the fourth order in Haeckel’s 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 swimming Hydroid-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 new 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 Thierstécke,” 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”’ +, I have laid down the position of matters 
and indicated that even the Hydrotd-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 work. 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, tom. i. (1878). 
+ Ibid. tom. v. (1883). 
13* 
