190 Prof. Carl Claus on the 
ception (Medusa-theory) does not in the smallest degree alter 
the theory of polymorphism.” 
When, therefore, Haeckel objects to the Medusa-theory 
that it ascribes to the developed Siphonophoran cormus only 
the value of a “‘ person” and regards the persons which con- 
stitute it only as organs (in the morphological sense), it has 
escaped him that I had already repeatedly shown how little 
any such deduction is founded in the theory itself, inasmuch 
as, in full accord with the requirements of his Medusome- 
theory, 7t has to regard the developed Siphonophore as a cormus 
composed of numerous polymorphic persons. When he further 
asserts of the Hydroid-theory that it goes too far and is wrong 
in ascribing to the different (morphological) organs of these 
persons the same value, he has forgotten to say that these 
deficiencies were already removed by the explanations given 
in these memoirs, and no longer existed in the conception of 
the theory supported by me, so that there was already a recon- 
ciliation of the two theories by which the supposed abrupt 
opposition between them had been cancelled. But had 
Haeckel taken account of the contents of my papers, not only 
would the reconcilement contained in his Medusome-theory 
have lost the appearance of novelty, but the essential thing, 
the true nature of the opposition of the two previous theories, 
and at the same time the coincidence of his Medusome-theory 
with the Medusa-theory, would have come to light. 
It was, however, consistent that Haeckel, in consequence of 
a representation made to him by Metschnikoff relating to the 
interpretation * of the Siphonophoran larva as a Medusa, 
was converted from the theory of Vogt and Leuckart, of which 
he had previously been a zealous adherent, to the Medusa- 
theory and transferred to this the polymorphism of the former. 
Nevertheless we might have expected from him at least a 
statement of the reasons why a swimming polyp-stock could 
not have been the phylogenetic origin of the Siphonophora, 
more especially as of late several arguments in favour of this 
view and in contradiction to the Medusa-theory have been 
brought forward. Instead of clearing away the difficulties 
raised by R. Leuckart and afterwards by myself and others, 
which are offered to this theory by the supposed dislocation 
of many parts of Medusz, and confuting the objections raised 
by me to the assumption that the sexual form of the Hydroid 
polype in its perfected form as a Medusa furnished the 
starting-point for the production of the Siphonophora, a series 
* “Studien tiber die Entwicklung Jer Medusen und Siphonophoren,” 
in Zeitschy, f. wiss. Zool. tom. xxiv. (1874) p. 38. 
