NATURE AND AFFINITIES OF THE SPONGES. 145 



polymorphic and flagellate cells first noticed by Dujardin. To a like cate- 

 gory must undoubtedly also be relegated the so-called "spermatic elements," 

 described by Professor Huxley in the 'Annals of Natural History' for the 

 year 1851. Lieberkuhn* corroborated and added considerably to the 

 details of the structure and life-history of Spongilla made known by 

 Dujardin, and elicited much new evidence concerning the occurrence in 

 this type of the motile ciliated germs, in addition to the more ordinarily 

 occurring non-motile and so-called "seed-like bodies," first discovered by 

 Dr. Grant, in association with various marine species, and merely recorded 

 by Dujardin, on the authority of M. Laurent, as existing in Spongilla. 

 Following upon Lieberkuhn's discoveries, must be recorded the very 

 important contributions respecting the ultimate structure of the closely 

 allied Indian species of Spongilla, contributed by Mr. Carter to the 

 'Annals and Magazine of Natural History,' during the years 1857 and 

 1859. In the first of these contributions, the entire life-history, from the 

 indurated " seed-like body " up to the adult state, was successfully traced 

 out, and many entirely new facts respecting the more minute histology of 

 the sponge organism elicited. Among these it was demonstrated that the 

 essential living constituents of the sponge-body were represented by the 

 ciliated monad-like elements first described by Dujardin, and that they 

 exhibited a very definite mode of arrangement. Under normal conditions, 

 Mr. Carter found that the monad cells were congregated together so as to 

 form a single and even layer within the interior of small spherical chambers 

 excavated within the sarcode or mucilaginous basal substance of the 

 sponge, and to which chambers he applied the term of "ampullaceous sacs." 

 The additional name of ovi-cells was also given to these chambers in their 

 earlier condition, from his having observed their development out of a 

 pre-existing ovule-like or granular mass, this latter first passing into the 

 normal, small, monociliated and unciliated sponge-cells which then spread 

 over the interior surface of the so-called ovi-cell, each with its cilium 

 directed inwards, and so leaving a cavity in the centre which finally became 

 connected with the nearest adjacent afferent canal. 



The origin of these " ampullaceous sacs," by a process of development 

 corresponding to the growth and segmentation of an. ordinary ovum, is, 

 as hereafter shown, entirely confirmed by the investigations of the present 

 author. Mr. Carter further demonstrated the capacity of both the ciliated 

 and unciliated sponge-cells of the ampullaceous sacs to take in solid 

 food in the form of minute granules of carmine distributed in the surround- 

 ing water, as also the possession by these individual bodies of contractile 

 vacuoles and nucleus-like granules. Taken as a whole, the animal nature 

 of Spongilla was now proved beyond further question, and its composition 

 maintained to consist essentially of polymorphic monadiform or amoeba-like 

 elements, closely corresponding with ordinary monads and amoebae, the 

 former being aggregated together in definite order within the structureless 



* Miiller's ' Archiv,' Bd. i., 1856. 



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