PENNATULA PHOSPHtWEA. 31 



says that tlie whole Pen may distend itself with water, the 

 distension heinj^ most marked in the stalk. He remarks that " no one 

 could anticipate the effect of intumescence from its form in a con- 

 tracted state." Also, that " it enlarges remarkahly as evening comes 

 on," Pennatulii being, according to him, " strictly nocturnal," and, at 

 any rate in captivity, only expanding fully in the evening or at night. 



Johnston* also notices that " when placed in a basin or plate of 

 sea-water, Pcnnatulce .... inflate the body until it becomes to 

 a considerable degree transparent, and only streaked with interrupted 

 lines of red." 



On the otherhand, Pancerif, who has made careful obsei'vations on 

 living Prnnatuhr, holds that this state of distension is not a natural 

 one. He says, " When these zoophytes, living at a depth of 40 or 100 

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

 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 Pennatulce 

 in this state respond exceedingly feebly to stimuli, whether mechanical, 

 chemical, themial, or electrical, to which, in their natural undistended 

 condition they answer readily. 



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

 this inflation of the stalk of Pennatula a constantly occurring or only 

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

 a normal or as an abnormal occurrence, due, as Panceri suggests, to the 

 exceptional conditions under svhich 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 bj' him at the time, that when one 

 of the PennatuUe — 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, driving 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, 



* Johnston: "British Zoophytes," Second Edition, 1817, Vol. ii., pp. 160-lGl ; 

 also, Figure 35, p. 158, where Pennatula phosphorea is figured with tlie stalk thus 

 inflated. 



+ Panceri : '• Etudes sur la Phosphorescence des Auiuiaux Marins," .\nnales 

 des Sciences Naturelles, Cinquieme Spvie. tome IG, 1872, p. 15. 



