ALCYONIDITJM ELECMNS. 61 



nected together that it is difficult to separate them. The foot of the 

 polypary is essentially nothing more than a continuation of these same 

 tubes modified in structure : those situated near the centre of the stem 

 have their walls only slightly thickened ; but those placed near the 

 periphery acquire a more solid consistence, from having their parietes 

 incrusted with innumerable fusiform spicula composed of carbonate of 

 lime imbedded in a cartilaginous substance ; these are arranged longitu- 

 dinally (fig. 26, 3), and give to the stem its solidity and peculiar aspect. 

 Near the circumference of this portion of the polypary longitudinal 

 fibres are perceptible, which appear to be the remains of tubes atrophied 

 by compression (fig. 27, 3, a). 



(129.) The tubes thus united in fasciculi are evidently analogous to 

 the cavities into which the polyps of Alcyons, Corals, &c., are retracted : 

 these have generally received the name of " polypiferous cells ;" and 

 some authors consider them as being quite distinct from the animals 

 inhabiting them : in the zoophyte under consideration, however, a very 

 superficial examination is sufficient to prove that they are really merely 

 continuations of the bodies of the polyps themselves, no line of demar- 

 cation being distinguishable between them. It is not, therefore, into 

 polypiferous cells that these little flower-like creatures retire, but be- 

 come retracted into their own bodies by a species of invagination ; and 

 the entire polypary which seems to afford them lodging is nothing but a 

 mass formed by the aggregated tubes of all the polyps belonging to it. 



(130.) It appears to be pretty generally admitted that among the 

 aggregated polyps nutritive materials swallowed by one individual goes 

 to the sustenance of the general community an opinion seemingly 

 based upon observations made upon certain Sertularian species : but 

 that a similar community of nutrition exists in the Alcyonidce re- 

 mained, prior to the researches of Milne-Edwards, an unsolved 

 question ; neither was anything known precisely as to the relation- 

 ship existing between these aggregated beings ; or, even admitting, from 

 analogy, the most intimate union, it was difficult to conceive how 

 nutritive matters were conveyed from one polyp to another, whether 

 by simple imbibition or in any other manner. 



(131.) In order to solve these questions so far as relates to the Al- 

 cyonidium under consideration, Milne-Edwards, by means of a small 

 glass tube having its end drawn out fine in the flame of a lamp, in- 

 jected a coloured fluid into the abdominal cavity of one of the polyps, 

 and found that the injection immediately passed into the abdominal 

 cavities of the polyps around; consequently the nutritive substances 

 swallowed by any individual can be distributed among the different 

 members of these remarkable colonies, so that food taken by one 

 may nourish the neighbouring animals. 



(132.) On cutting one of these polyps open under a magnifying 

 glass, it is easy to explain how this intercommunication is effected : it 



