round the Ct'U'um of the Sjwnge-ceU. \\ 



hence tlic j)riniar)' globular or rounded fonn of Aimvlxi in 

 the passive state. 



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

 S{)onjre-cell of /.tMCo.so/rnm botryoide^ (/. c. p. 22), that " tlic 

 mouUi i.s the only organ which has not been actually observed, 

 although itd j)osition 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 constiiutly whirled in by the tiagella and made to 

 impinge upon the area within the collar." 



Aa regards Codosiga pukherrima and Salpingrrca gracilis, 

 the intelligent author adds {i. c. p. 15) : — " The viou(h\ we are 

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

 somewhere about the base of the tlagellum. 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 fsecal matter." And of Salpingceca it is stated 

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

 suggested, may possibly be coincident with tlie mouth, is 

 easily determined, even to the naiTowest limits, as the laical 

 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 Leucosohnia 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 tlie 

 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 Difflugia, or from any part of the 

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

 that we may infer that these pseudopodia may have, under 

 such conditions, the power of introccptiug particles of food at 

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

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

 only, and there introcepted, as 1 delineated in 1857 (/. 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 pseudopodia! prolongation ap- 

 pears to become a pointed organ of suction like the tentacular 

 prolongations from Podophrya fixa 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- 



