146 NATURE AND AFFINITIES OF THE SPONGES. 



jelly-like sarcode, that formed the groundwork or substratum of the 

 sponge-body. Within the central substance of this sponge-body, and 'also 

 in the superficial part, called by Mr. Carter the investing membrane, were 

 found scattered the innumerable amoeba-like non-flagellate cells, as also the 

 characteristic spicules of the species, which were reported to be secreted 

 by the amoeboid elements. Finally, the entire sponge-body was shown 

 to be brought into intimate relationship with the external water, firstly, by 

 a series of pore-like apertures opening or closing at will in the investing 

 membrane, and communicating through the afferent canals with the am- 

 pullaceous sacs ; and secondly, by another series of tubular channels, the 

 efferent canals, which originating in the deeper substance of the sponge, 

 united with each other, and finally debouched upon the large excurrent 

 apertures or " oscula." 



As a result chiefly of the very exhaustive evidence concerning the 

 ultimate structure of Spongilla elicited through Mr. Carter's investigations 

 as here briefly epitomized, the position of the sponges among the ranks 

 of the Protozoa, and as specialized and colonial aggregations of amoeboid 

 and monadiform Protozoic beings, became almost universally accepted. 

 It is at the same time worthy of notice, that Mr. Carter hinted at the 

 possible correspondence of the ciliated sponge-chambers or ampullaceous 

 sacs with the stomach-cavities of the simplest polyps, certain Planariae, 

 and other organisms in which the cavities receiving the injected food are 

 also lined with cilia. In January 1859, Mr. Carter contributed a further 

 communication to the journal already named, recording new data of interest 

 relative to the form and structure of the essential monadiform sponge-cells, 

 though at the same time he temporarily modified his previous views con- 

 cerning the character of the ampullaceous sacs. The most important point 

 that requires notice relates to the circumstance that he here described and 

 figured in association with certain of the larger ciliate or monadiform 

 sponge-cells, the existence of two " spines " or " ear-like points," which he 

 figured and described as projecting to an even distance on either side of 

 the base of the single whip-like cilium. A possible spermatozoic character 

 of these so-called "spiniferous cells" was at first suggested by Mr. Carter, 

 but subsequently abandoned through his demonstration of their capacity 

 to take in solid nutriment. The special interest attached to the discovery 

 by Mr. Carter of these spiniferous elements will shortly become apparent. 



The earliest complete treatise of importance demanding notice bearing 

 upon the structure and organization of sponges, is the first volume of 

 Dr. Bowerbank's ' Monograph of the British Spongiadae,' published by the 

 Royal Society in the year 1864. Vast, however, as is the mass of material 

 embodied in this and the two subsequent volumes of this work (1866 and 

 1874), it relates almost entirely to the structure and organization of sponges 

 in their dried or preserved condition, and is of practical value only for the 

 purposes of specific identification. In such preserved specimens, as there 

 described, the essential vital elements now under discussion had become 



