144 



NATURE AND AFFINITIES OF THE SPONGES. 



the sponges, it is, before all things, desirable to commence with an exami- 

 nation of the earlier periods of their intelligibly recorded history, and 

 thence to trace forwards, link by link, those consecutively recorded data 

 which have led up to the present controversial position of the question. 



As an initial step in this direction, it is worthy of remark that the 

 conclusive demonstration of the very animal nature of the Spongida has 

 only been accomplished within the present generation ; for while originally 

 premised by Marsigli at the commencement of the eighteenth century, 

 and subsequently advocated by Ellis and Solander, Montagu, and Lamarck, 

 it was left to Grant, Bowerbank, Carter, Lieberkuhn, and Dujardin within 

 these later limits to produce the actual proofs of their animal organization. 

 Among the investigators just enumerated, the name of our fellow-country- 

 man Dr. Grant may be specially singled out, as the authority who first 

 discovered the characteristic ciliary action in sponges, as also the existence 

 of the remarkable free-swimming ciliated reproductive bodies described at 

 length later on. That of Felix Dujardin, however, has to be still more 

 prominently mentioned, he having been the first to indicate that relation- 

 ship between these organisms and the more ordinary Flagellate Protozoa, 

 which with some modification is here supported. In the course of his 

 ' Histoire des Infusoires,' published in the year 1854, this author devotes 

 two brief pages to the nature and organization of the group now under 

 consideration. Tearing to pieces a living fresh-water sponge {Spongilla 

 lacitstris), he there records that the constituent living particles will be 

 found, on submission to microscopical examination, singly or united in 

 groups, either floating in the water or adherent to the glass slide, and 

 that for the most part these constituents are furnished with long vibratile 

 filaments or flagella, similar in character to those possessed by the simplest 

 Flagellate Infusoria or monads. These same constituent particles, he, 

 moreover, observed to throw out lobe-like expansions or pseudopodia, and 

 to creep about after the manner of amoebae. This phenomenon, while 

 possessed by the floating ones, is more especially marked in those which 

 adhere to the surface of the glass, and in which the vibratile flagella had 

 become withdrawn or obliterated. He also briefly alluded to the ciliated 

 reproductive bodies of Spongilla and various marine sponges, and the group 

 as a whole he declared to exhibit a type of organization comparable to 

 associated colonies of Infusoria, possessing the united characteristics of 

 both monads and amoebse. Respecting the horny fibres and siliceous or 

 calcareous spicules secreted by the various tribes of sponges, Dujardin 

 suggested that they are analogous respectively to the branching and some- 

 what horn-like supporting stalk of such monads as AntJiopJiysa, and to the 

 siliceous and calcareous tests presented by the ordinary Rhizopoda. 



By Mr. Carter, in November of the same year 1854,* the announce- 

 ment was made of the discovery, in Spongilla, of so-called zoospcrm-like 

 bodies, these, however, as he afterwards admitted, representing the ordinary 



* 'Ann. and Mag. Nat. Hist.,' vol, xiv. ser. ii. 



