190 Prof. Carl Glaus 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 1 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, it has to regard the developed Sijyhonophore as a cormus 

 covqwsed of numerous polyino7'phtc 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 tlie 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 translerred 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 Medus£e, 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 iiber die Entwicklimg ier Medusen und Sipbouophoren," 

 in Zeitschr, f, wiss. Zool. toru. xxiv. (1874) p. 38. 



