THE ''SAILING'' OF THE NAUTILUS. 83 



residing in Messina, having succeeded in keeping alive for a 

 time an argonaut the shell of which had been broken in its 

 capture, discovered that the animal quickly repaired the 

 fracture, and reproduced the portions that had been broken 

 off. Induced by this to make further experiments, she 

 kept a number of living argonauts in cages sunk in the 

 sea near the citadel of Messina, and in 1836 laid before 

 the " Academy " at Catania the following results of her 

 observations of them : — 



1st. That the argonaut constructs the shell which it 

 inhabits. 



2nd. That it quits the Q:^g entirely naked, and forms the 

 shell after its birth, 



3rd. That it can repair its shell, if necessary, by a fresh 

 deposit of material having the same chemical composition 

 as its original shell. 



4th. That this material is secreted by the palmate, or 

 sail, arms, and is laid on the outside of the shell, to the 

 exterior of which these membranous arms are closely 

 applied. 



Madame Power was mistaken on two points. Firstly, 

 the construction of the shell does not commence after the 

 birth of the animal, but, as has been shown by M. 

 Duvernoy, its rudimentary form is distinctly visible by the 

 aid of the microscope in the embryo, whilst still in the 

 &gg ; and secondly, she continued to believe in the use of 

 the membranous arms as sails, and of the others as oars. 

 This fallacy was exploded by Captain Sander Rang, an 

 officer of the French navy, and " port-captain " at Algiers, 

 who carefully followed up Madame Power's experiments, 

 and confirmed the more important of them. Thus were 

 set at rest questions which for centuries had divided the 

 opinions of zoologists. 



G 2 



