round the Cilium of the Sponge-cell. 11 



hence the primary globular or rounded form of Amoeba in 

 the passive state. 



Be this as it may, Prof. James-Clark states, respecting the 

 sponge-cell of ZeMcosoZema hotryoides (?. c. p. 22), that "the 

 mouth is the only organ which has not been actually observed, 

 although its position has been inferred, not only from the 

 otherwise similar structure of the monad of this creature to 

 that of Codosiga (§6), but because currents of floating parti- 

 cles are constantly whirled in by the flagella and made to 

 impinge upon the area within the collar." 



As regards Codosiga pulcherrima and Salpingoeca gracilis^ 

 the intelligent author adds {I. c. p. 15) : — " The mouth, we are 

 obliged to presume, as we did in regard to Codosiga, lies 

 somewhere about the base of the flagellum. Abundant diges- 

 tive vacuoles were observed, as well as loose particles of food, 

 in various parts of the body ; but at no time were we so for- 

 tunate as to see the introception of nutritive material or the 

 ejection of feecal matter." And of Salpingoeca it is stated 

 (p. 11), "the position of the anus, which, as I have already 

 suggested, may possibly be coincident with the mouth, is 

 easily determined, even to the narrowest limits, as the fascal 

 matter is discharged in large, highly refractile pellets (fig. 

 24^, d) close to the base of the flagellum." 



Such is the only evidence we possess of the existence of 

 distinct oral and anal orifices respectively within the collar of 

 the sponge-cell of Leucosolenia hotryoides ; and so long as the 

 collar of the sponge-cell is present with the cilium, all parti- 

 cles of food may go into and out of the body through the 

 collar ; but as every part of the sponge-cell is polymorphic, 

 and may put forth pseudopodia from one part in particular 

 (PI. II. figs. 22, 23, 24), like JJiffiugia, or from any part of the 

 body (PI. I. figs. 14, 6 & 16, a), like Amoeba, so it seems to me 

 that we may infer that these pseudopodia may have, under 

 such conditions, the power of introcepting particles of food at 

 any point, which, while the cilium is unretracted and in full 

 motion, may be thrown back upon the body towards its base 

 only, and there introcepted, as I delineated in 1857 {I. c). 



This, then, would at one time make the sponge-cell a fla- 

 gellated infusorium, and at another a rhizopod ; but being 

 compounded of the two, it is certainly neither, but an organism 

 sui generis — in short, the sponge-cell. 



On some occasions, too, the pseudopodial prolongation ap- 

 pears to become a pointed organ of suction like the tentacular 

 prolongations from Podophrya Jixa and Acineta, when it may 

 seize and penetrate the body of another infusorium for the 

 purpose of extracting its nutritive contents. (Indeed it is pro- 



