406 Original Articles. [July, 



single Hydra, and is the result of a continued process of gemmation. 

 Nutriment is procured for the commonwealth by the labours of the 

 multitudinous polypites, is prepared in their stomachs, as in so 

 many laboratories, and is then distributed to all parts of the struc- 

 ture, through a channel which permeates the trunk and every branch 

 and branchlet. So much may suffice as a sketch of the general 

 character of the tribe. Our present concern is with the reproductive 

 history in which the facts occur that may be said to have a popular 

 interest. 



If we were in search of a complete contrast to the staid and sta- 

 tionary Zoophyte in external appearance and in mode of life, we 

 might find it in those exquisite little crystal globes, which, bright and 

 frail as the bubble, dance so gaily through the waters of the sea, and 

 are known to the naturalist as Medusae. On casual inspection, the 

 two organisms seem to have nothing in common. The one is rooted 

 to a point of space, the other is free of the wide waters, and seems 

 almost to have realized perpetual motion. The one is all but univer- 

 sally compound, the other single. But why speak of differences, when 

 there is not a point of apparent resemblance ? Systematists till re- 

 cently never dreamt of any connection between them, but grouped 

 them in two distinct Classes. The observations of Wagner, Sars, Dal- 

 yell, Steenstrup, and others which showed that certain Medusae of the 

 simpler or naked-eyed division are borne as buds on certain plant-like 

 Zoophytes, and are in some sense the progeny of beings so unlike 

 themselves, were a startling surprise. We are now familiar enough 

 with the fact, but have only lately discovered its real significance. 



We now know that a very large proportion of the so-called naked- 

 eyed Medusae, if not all of them, are at one period of their existence 

 in organic connection with some Hydroid stock, from which they bud 

 just as the polypites do, but from which they are also detached at a 

 certain point of their development, and in their free state mature the 

 elements essential to the reproduction of the species, scattering the 

 embryos, the seed of new colonies, at a distance from the original 

 settlement. 



Now, to comprehend this history, we must do two things : 1st, we 

 must discard any conceptions we may have formed of the Medusae as 

 independent organisms — as perfect animals ; and, 2nd, we must 

 recognize the essential structural identity of the polypite and the 

 medusoid. 



Professor Huxley long ago took exception to the term Medusa, as 

 the designation of the free sexual zooid of the Zoophyte, rightly 

 in*ging that it tended to perpetuate an erroneous view of its nature. 

 It should have a name that expresses its relation to the life-series, 

 of which it is but a single term, and that suggests no thought of posi- 

 tive independence. We believe that it will be better to dismiss both 

 Medusa and Medusoid from our nomenclature, and thus to get rid of 

 the false associations that have gathered round these terms as a 

 nucleus. Professor Allman, to whom we are indebted for an exhaustive 

 report on the reproductive history of the Hydroida, and whose name 



