REPOKT ON" THE PEXXATULIDA. 125 



metres (22 to 54 fathoms), or more, are suddenly removed from their 

 natural resting place at the bottom of the sea, and transferred to an 

 aquarium, they undergo so great a change in the pressure, temper- 

 ature, degree of saltness of the water, and conditions of existence 

 generally, that they swell up gradually to an enormous extent — up to 

 double their natural size." He brings forward as further evidence that 

 this dropsical condition is an unnatural one, the fact that Peiutatuhe 

 in thisstate respond exceedingly feebly to stimuli, whether mechanical, 

 chemical, thermal, or electrical, to which, in their natural uudistended 

 condition they answer readily. 



The above tjuotations suggest two points for consideration : — (1.) Is 

 this intiation of the stalk of Peimutulu a constantly occurring or only 

 an exceptional phenomenon ? (2.) If constant, is it to be regarded as 

 a normal or as an abnoj-mal occurrence, due, as Panceri suggests, to the 

 exceptional conditions under which the Pen is placed ? 



Concerning- the first point, the united testimony of Dalyell, 

 Johnston, and Panceri proves that at any rate this inflation is no rare 

 event under the conditions named; and through a valuable observa- 

 tion of Mr. J. F. Goode, who kept the log of the Oban excursion, we are 

 enabled to give some account of the process of inflation as it actually 

 occurred in one of the Oban specimens. We learn from Mr. Goode's 

 MS. notes and from a drawing made by him at the time, that when one 

 of the Pennatithe — the male specimen — was placed, immediately after 

 its capture, in a shallow pan of sea-water, the stalk was at first 

 cylindrical with a slightly bulbous extremity (very similar to Figs. 1 

 and 2) ; but that shortly afterwards " it was seen to undergo a gradual 

 change of form. A slight constriction took place near the extreme 

 end, di'iving the fluid contents forward towards the upper part (near 

 the rachis), which became much swollen, leaving only a small bulb at 



the opposite end This form was not at all permanent, 



continued change still going on, evidently with the object of regaining 

 its original fonii, the fluid seeming to oscillate from one end to the 

 other. The above changes took place in the flrst twenty minutes from 

 the time of capture." 



With regard to the second point, which can, of course, only be 

 settled by direct observations on living specimens, we will only 

 remark here that Mr. Goode's obsei'vation that at the moment of 

 capture the proportions of the stalk were those we have decribed and 

 figured from spirit specimens, is important testimonj' in favour 

 of these proportions being the normal ones ; and further, that 

 Panceri's suggestion appears to us to be of much weight, and that 

 it is quite possible that it also gives the clue to Sir John 

 Dalyell's statement concerning the " nocturnal habits " of Peti- 

 natuUe. The bottom of the sea at twenty to forty fathoms 

 depth must be very dark indeed as compared with the surface, and it 

 seems to us very probable that a Peniuitulu " in a basin or plate of 

 sea-water "" does not expand its polypes full\ until the e\eiiing. simjily 



