240 Physalia Pelagica. 



their prey in a similar manner to those of some kinds of actinse, 

 which have also a power, not precisely of lengthening the 

 tentacles themselves, but of shooting forth from them a slender 

 thread to a very great distance, the end of which is so con- 

 structed that on touching its destined prey it benumbs it like 

 the tentacle of the Physalia. In several of the Medusas also, it 

 may be recollected that a similar power is possessed of shooting 

 forth filaments from those dangerous pendent locks from which 

 their name is derived. The Cyanea capillata, for instance, 

 which drifts to the English shores after storms, being one of 

 the most dangerous ; and its tawny fibrous mass when seen 

 floating on the water or lying on the beach should therefore be 

 carefully avoided. It appeared also, on watching the actions of 

 the Physalia in the tank, that it had no control over the direction 

 of its own course, which seems to prove, judging from its powers 

 when in confinement, that in the open sea it must be governed 

 entirely by the wind, the wave, or the current. 



More recent investigations, however, have induced some natu- 

 ralists to consider that the suckers, or feeding tentacles, are also 

 to a certain extent organs of locomotion, and that at the same 

 time they act as brancheee, or breathing organs. It has also 

 been suggested that these creatures, as occurs in several of the 

 lower kinds of animal life, may, in the course of then develop- 

 ment, undergo several material changes of form, so as to exhibit 

 at different periods striking differences, not only in their internal 

 structure, but also in their exterior aspect. If such be the case, 

 the Physalia may, as yet, have been described as a complete 

 animal, whereas the expanded, or bladder- form of its existence, 

 may only be its last phase of development, during which several 

 organs may have disappeared, or have been only rudimentary; 

 just as the ventral legs of the caterpillar disappear in the per- 

 fect insect, while the wings and antennas of the butterfly or 

 moth already exist within the body in a rudimentary state. 

 This supposition may serve to explain the different opinions 

 of naturalists on several points of Physalean structure, and 

 for the points of difference described by M. Lesson in his 

 Histoire Naturelle des Acalejplies, published in 1843, ten years 

 later than the remarks of Mr. Bennett. The principal diffe- 

 rences which occur in the anatomical descriptions of these 

 eminent naturalists are, first, that M. Lesson conjectures that 

 the sudden injection of the long tentacles with a fluid forms the 

 principal cause of their power of excessive extension ; and 

 secondly, that he actually has discovered a distinct central food 

 reservoir, or stomach, not perceived by Mr. Bennett. M. Lesson 

 states that, running along the base of the air-bladder, which 

 is of much thicker texture than the upper part, he detected 

 a digestive tube covered above by a membranous fold, and 



