The Argonaut. Paper Nautilus 



from inquisitive mankind? As late as 1850 little more was 

 known about it than Aristotle wrote four centuries before Christ. 



The ancients noticed that the shell has no muscular attach- 

 ment to the body. The mollusk relaxes its hold when handled 

 and the shell slips away. Wise people said: "Here we have a 

 parasite like the hermit crab, that has picked up a shell and 

 moved into it." But nobody could clear up the mystery of the 

 shell. Where and what was the mollusk to which it rightfully 

 and originally belonged? Nobody could say with certainty. 

 Nor could anybody say whether the ship-wrecked Argonaut 

 could live without the shell. Nobody ever saw a male Argo- 

 nauta. The specimens seen were all females. 



About the middle of the nineteenth century scientific interest 

 in the paper nautilus reached white heat. Two of the leading 

 zoologists of the time tried to convince all the rest that the 

 argonaut has no means of secreting a shell. They believed the 

 shell to be that of a large sea snail. The arguments upholding 

 these theories were very clever, but facts were lacking. 



Another mystery appeared for solution. A long, wriggling, 

 whip-like object was found hiding in the folds of the mantle. 

 It looked like the arm of an octopus, and was full of spermatozoa. 

 Some authors believed it to be a parasite; others jumped joyfully 

 at the conclusion that at last they had found the male argonaut. 



While these men argued, a lady at Messina, Italy, was closing 

 a long series of observations on the development of Argonauta. 

 It is not difficult to keep the eggs in a marine aquarium and to 

 watch the young ones grow up. Madame Jeannette Power saw 

 the eggs hatch perfectly formed and very active young, which 

 exhibited no sign of a shell. In ten or twelve days the shell was 

 observed to be forming in some individuals. 



This shell is a strange and unusual one. It is not truly a 

 shell at all, but a ciadle secreted to protect the eggs in the breed- 

 ing season. The male has no shell. The shell glands of mollusks 

 are in the mantle edge. Here is a unique exception. The two 

 dorsal arms spread out into large webs at their extremities. 

 These two thin "vela" have the shell glands; the mantle has 

 none. When the young female is one inch long it begins to form 

 a shell. The body rests in the mouth of the shell, though it ex- 

 tends pretty far out of it, and the two inflated web-like arms 

 always clasp the two sides of the shell tightly, and deposits of 



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