PROF. OWEN ON THE ARGONAUT. 425 



" Mr. Owen then proceeded to state that he had dissected every specimen 

 in the present collection, in which the absence of ova in the shell left the 

 sex doubtful, and that they all proved to be females ; this fact rendered it 

 allowable to conjecture that the calcifying brachial membranes, and con- 

 sequently the shell, might be sexual characters, and peculiar to the female. 

 But, he argued, k the known paucity of males as compared with females in 

 other species of cephalopods, rendered the conjecture to a certain degree 

 problematical. Should it, however, be hereafter proved that the male ar- 

 gonaut possessed neither a shell nor the organs for secreting it, this fact 

 would not render the hypothesis of the parasitism of the female, which does 

 possess the calcifying membranes, at all the less tenable.' 



" With respect to the shell of the argonaut, Professor Owen observed that 

 ' any argument founded on observations on the dried shells in cabinets, 

 could tend only to mislead the observer. Madame Power's specimens hav- 

 ing been recently collected, and preserved in alcohol of not too great strength, 

 manifested much of the original transparency and elasticity of the living 

 shell. It was obvious, therefore, that light would act in developing the 

 coloured spots on the contained body of the argonaut ; and this fact is im- 

 portant in reference to the seventh argument in M. de Blainville's memoir 

 of 1837, p. 4., in which he asserts that ' those parts of molluscs which are 

 covered with a shell are constantly white or colourless, but the mantle in- 

 vesting the body of the argonaut is highly coloured.' Now, if M. de Blain- 

 ville's object had been to prove that the Ocythoe did not inhabit a shell at 

 all, the force or purport of this observation would have been intelligible ; 

 but the question is not whether the body of the Ocythoe is or is not covered 

 with a shell, but whether it makes or steals that shell. But perhaps the 

 argument, founded on the supposed opacity of the argonaut shell, was 

 brought forward merely to prove, that up to a certain period of its exist- 

 ence the Ocythoe was naked, and that the argonaut-shell was taken posses- 

 sion of only for some temporary purpose, as for ovipositiom The observa- 

 tions, however, which I published in 1836 (Cycl. of Anat., Art. Cephalopo- 

 da, p. 544), proved that the young cephalopod of the argonaut was provided 

 with a shell prior to the period of oviposition, and that the body entirely 

 filled the shell at that period. The present collection still more satisfacto- 

 rily establishes the fact, that the argonaut-shell is not assumed by the ce- 

 phalopod for a temporary purpose ; for the shell which protects the young 

 would be wholly inadequate as a nidus for the ova of the mature animal ; 

 and for what purpose, then, on the parasitic theory, is the shell assumed by 

 the cephalopod before its ovarium has received the stimulus of sexual de- 

 velopment ? ' 



" In Madame Power's recently-collected specimens the shell, after a few 

 hours' soaking in water, regained so much of its original flexibility as to 

 demonstrate its power of varying its form with the varying bulk arising 

 from the respiratory and locomotive actions of the inhabitant. 1 



" The inductions, therefore, which the present collection of argonauts of 

 different ages and sizes legitimately sustained, were in exact accordance 

 with Madame Power's belief that the cephalopod was the true constructor 



1 In M. de Blainville's Letter on the Parasitism of the Argonaut (1837), 

 the following assertion is offered as the tenth argument: — ' La mode de lo- 

 comotion et de respiration de ces animaux par la contraction et la dilata- 

 tion alternatives du sac, ne permet pas d'admettre qu'il y ait adherence de 

 la peau avec la coquille, a moins que de supposer que celle-ci soit flexible 

 et elastique, et suive tous les mouvemens de celle-la, ce qui est bien loin 

 de la verite. ' 



