61 



OCTOPODA. 



OCTOPODA. 



62 



membranous at the extremity. Funnel without a valve, but articu- 

 lated at its base by two ball-and-socket joints to the inner sides of 

 the mantle. Branchial hearts with fleshy appendages. No internal 

 horny or testaceous rudiments ; but an external monothalamous sym- 

 metrical shell, containing, but not attached to, the body of the animal, 

 which also deposits its eggs in the cavity of the shell. (Owen.) 



Argonauta Argo has been from the earliest periods an object of great 

 interest to zoologists, in consequence of the accounts of its sailor-like 

 habits handed down to us from the ancients we need only refer to 

 the statements of Aristotle, Pliny, ^Elian, Oppian, and others and in 

 consequence of the difference of opinion entertained with regard to 

 the inhabitant of the shell by naturalists ; some holding that the 

 Cephalopod found in it was a mere parasite, or, even worse, a pirate 

 that had destroyed the legitimate owner and possessed himself of the 

 shell ; and others, that the animal waa the lawful possessor and 

 original constructor of it. 



Among those who supported the former opinion were Lamarck, 

 De Montfort, Ranzani, Poll, and De Ferrussac, to say nothing of 

 Cuvier, the inclination of whose mind evidently was that the shell 

 belonged to the animal, though he only designates the opinion of those 

 who held the contrary as extremely problematical. Professor Owen 

 appears to have been early inclined to this view of the subject. 

 Dr. Leach, M. Rafinesque, M. De Blainville, and Dr. Gray stand con- 

 spicuous among those who denied that the Ocythoe found in the shells 

 of the genus Argonauta of Linnaeus was the constructor of the shell. 



The reasoning of those who held that the Argonautic Cephalopod 

 was the constructor of the shell appears to have been based upon the 

 numbers found always fitting the shell, and, in the case of Poli and 

 De Ferruasac, upon the supposed discovery of the animal and shell in 

 the egg. 



Those who opposed these views, or still doubted, were struck with 

 the supposed anomaly which would be manifested if the Cephalopod 

 really were the natural inhabitant. Evidence that the animal was not 

 affixed to the shell had been given over and over again, till it became 

 largely cumulative, and had never been controverted. The animal 

 had been seen to quit it when alive, and to fall out when dead by its 

 own weight upon reversing the shell. How then was the shell to be 

 secreted ,' Again, the specimens found in the greater majority of the 

 shells were apparently females, and placed upon a great mass of eggs, 

 which filled up at least all the spiral part of the shell ; and on these 

 the body of the animal rested. An Octopui, nearly allied to ' 

 was caught in the Madras Roads with ita ventricose body firmly im- 

 bedded in a ghee-bowl ; and Octopui arenarita had been found in a 

 Dolium. These and other facts, with which we will not weary the 

 reader, seemed very powerful ; but if any credence is to be given to 

 the carefully-conducted experiments of the lady whose valuable 

 observations we shall now proceed to notice (and, after strict scrutiny, 

 we see no reason to view them with the slightest suspicion), the 

 question is now set at rest, though it waa not by Poli, who must, if 

 this lady's experiments were correctly marie and accurately reported, 

 have been in error when he supposed that he saw the animal and shell 

 in the egg. 



In 1836 Madame Jeannette Power laid before the academy at Catania 

 her ' Osservazione Fisiche sopra il Polpo dell 1 Argonauta Argo,' in 

 which, after a long and careful course of inquiry, she declared the 

 following results : 1st, that the cephalopodous mollusc usually found 

 therein is the constructor of the shell which it inhabits ; 2nd, the 

 clearing up of the doubts with regard to the first development of ite 

 eggs ; 3rd, new facts respecting its habits. 



In order to obtain the data from which Madame Power came to her 

 important conclusions, she had cages constructed which were eight 

 palms long and four palms broad, with a convenient interval (three or 

 four lines; between the bars, which allowed the water to enter freely 

 when placed in the sea, whilst the escape of the animal was prevented. 

 Madame Power placed these cages on a shallow bottom in the sea near 

 the citadel of Messina, where she could examine them undisturbed, 

 and inclosed in them a number of living Argonauts, which she supplied 

 every two or three days with food, consisting of naked and testaceous 

 molluscs. 



The following is this lady's description of the Cephalopod of the 

 Argonaut : " It is furnished with eight arms, having on each two 

 rows of suckers ; the first two arms are more robust than the others, 

 and should be so, because they serve as masts to support the sails, 

 which, spread out, act before the wind as such. At the base they 

 have on the inferior sides the double row of suckers, like the other 

 six ; but from the inferior row, at about an inch from the base in 

 adults, a rather furrowed membrane begins to develop itself, which 

 extends as far as the tip of the arm, and, holding it bent, it can no 

 longer execute the office of a rowing arm, but is employed by the 

 animal as a sail. These sails are so large that, when turned backwards 

 and pressed against the shell, they can entirely cover and protect it. 

 Thus, as far as I can conclude, the true office of these sails is exactly 

 that of keepinz themselves applied to the shell at all times, in reserve 

 for the moment when the animal, coming to the surface of the water, 

 removes them, and, spreading them, raises them as sails. In fact, the 

 series of suckers of the sail-arms, when the membrane of the sails is 

 wrapped about the shell, is placed exactly over the keel of it in such 

 manner that each sucker corresponds to each point in which the 



ribs of the shell terminate, until they reach the two margins of the 

 spiral." 



Madame Power compares these sails with the two wing-like lobes of 

 the mantle of Cyprtea, [CirRiEiDx], not only from the manner iu which 

 they cover the shell, but because she has reason to believe that the 

 formation of the shell is the result of a trausudation from the mem- 

 brane of the sails, the corrugations of which, iu secreting the calcareous 

 matter, may be the cause of the ribbed form of the shell. 



This consideration, she remarks, may weigh in obviating the diffi- 

 culties of those who cannot imagine how a shell containing a cepha- 

 lopod should present no resemblance with the folds of the animal 

 compressed within it. For if they would consider it the result of a 

 calcareous deposition of the membrane of the sails, they would find 

 not only the series of little points corresponding to the suckers, which 

 adapt themselves to the keel of the spiral, but an explanation of the 

 disposition of the ribs, and of the smooth and paper-like condition of 

 the shell. 



The sail, when spread out, presents, according to Madame Power, a 

 silvery surface, speckled with concentric circles of spots, with a black 

 spot in the middle, surrounded with a beautiful gold colour; this and 

 the vicinity of the suckers along the keel and the spiral assume a 

 purple colour so vivid that it approaches that of the Janthina. The 

 mouth, the head, the bag, and the branchiae, did not present Madame 

 Power with any novelty beyond what had been already well described 

 by naturalists, and which is common to the Cuttles and the Cala- 

 maries ; but she makes two observations with regard to the funnel, 

 which she believes to bo new : that it fulfils the office of a pump 

 or proboscis rather than that of a funnel, and that the animal employs 

 it, when swimming with its arms on the surface of the water, as a 

 helm, elongating it in front of the widest part of the shell, at the same 

 time that the spiral serves as a prow. 



" Reflecting," says Madame Power, " on the delicacy and fragility 

 of the shells, and wishing to trace the cause of their being so rarely 

 seen broken, I determined to touch one whilst its poulp, or animal, 

 was within ; and taking it dexterously between my fingers, to learn 

 what degree of flexibility it would admit, I discovered that it was 

 extremely pliant, so much so as to admit of the two extremities of 

 the great curve being brought into contact without breaking; and 

 indeed shells so fragile ought to possess this flexibility, in order that 

 they might not be continually liable to be broken in pieces by the 

 restless and uninterrupted movements of their poulps, as well as by the 

 shocks which they would be likely to suffer in the depths during a 

 stormy sea. In this case it would prove very unfortunate for them, 

 as they are not capable of forming an entire new ahull. 



" Having ascertained the flexibility of the shell whilst the living 

 animal was within, I immersed some empty ones which had been 

 exposed to the air for some time in fresh water, and, at the end of 

 three days, found them as pliant and flexible as at first. 



" As regards the connection between the animal and the shell in 

 which it is housed, I have not found any ligament or muscle which 

 connects them ; while the sac is simply held by the turning of the 

 end of the spiral, from which it may be easily separated; and it 

 appears that the tight adhesion of the sac against the internal surface 

 of the ribs of the shell is sufficient to hold it attached. Moreover 

 the external superposition of the sail-arms keeps the shell firmly upon 

 the poulp." 



Madame Power states that Argonauta Aryo in its natural state is 

 to be found in the neighbourhood of Messina, and even in the port, 

 almost all the year through, in larger or smaller numbers. Their true 

 season she considers to be autumnal, or in the months of September, 

 October, and November. It may be, in her opinion, either because 

 the current brings them at that time, or that food is more plentiful , 

 or because it may be the season of their fecundation. They are seen 

 in the most muddy parts of the port and where the anchored boats 

 lie thickest. When the Argonauts are on the surface of the water, if 

 they observe any person, they fold the sail-arms over the shell and 

 stow the rowing-arms inside it : then they sink to the bottom. If 

 they are beneath the surface, they eject ink, like other cephalopods, 

 to make the water turbid, thus gaining time to hide themselves in the 

 mud. 



Those in the cage, when closely pursued, would, after ejecting their 

 ink, spirt out water from the tube, and then shrink into the shell, 

 which was covered with the sails. At first the appearance was silvery, 

 but instantly afterwards a purple colour would spread along the 

 suckers over the whole of the keel and spiral, and concentric circles of 

 spots would show themselves upon the two surfaces. 



During calms and when the water was quiet, they would, if not 

 conscious of being observed, exhibit their many beauties, rowing along, 

 their full sails tinged with elegant colours, resting the extremities of 

 the sail-arms on the two sides of the shell or embracing the shell 

 with them. Sometimes, when pressed by hunger, they would come 

 almost to the surface of the water, and when Madame Power offered 

 them food, they would snatch it out of" her hands and greedily 

 devour it. 



With regard to the formation of the shell by the young Argonaut, 

 Madame Power repeated the experiments of Poli iu the company of 

 Dr. Anastasio Cocco of Messina and other persons, but nothing more 

 was found than a group of eggs in each individual, similar to millet- 



