8o4 CLASS HI. TENTACULIFERA. 



material of its captured prey is brought about on an entirely distinct principle. 

 The interpretation arrived at by Maupas in this connection is indeed of such 

 importance that a quotation in extcnso from his description of this process may 

 be appropriately introduced. Referring especially to the above species named, he 

 states : — 



" When an Infusorium is securely caught by an Acinetan and held at the extremity 

 of one of its tentacles, a rupture is produced in the cuticle of the victim at this 

 point of contact. The axillary substance of the tentacle penetrating this perforation 

 then passes into the body of the Infusorium, and probably accelerates its death. 

 The tentacle now increases greatly in thickness, this thickening being without doubt 

 due to the afflux of sarcode from the body of the Acinetan, and of which indeed the 

 axillary substance of the tentacle is but a continuation. A current is thus established 

 from the Acinetan in the direction of its prey, which is, however, not visible in con- 

 sequence of the transparency and freedom from granulation of the sarcode stream. 

 On penetrating the body of its victim this sarcode mixes freely with that of the 

 captured prey, and loading itself with all assimilable substances, returns to its point of 

 departure and thus produces the inflowing current that is so distinctly seen by 

 reason of the opaque granular particles held in suspension."' M. Maupas proceeds 

 to explain that this phenomenon is directly comparable with the sarcode circulation 

 observable in the extended pseudopodia of the Foraminifera, or with the intracellular 

 rotation or cyclosis in certain vegetable cells. The chief difficulty in the way of 

 such interpretation consists, he admits, in the fact that in the tentacle of the 

 Sphccrophrya an incurrent stream is alone visible, while in the pseudopodium of a 

 Foraminifer one in each direction is distinctly developed. Such apparent incon- 

 sistence is, however, explained by the fact above mentioned that the excurrent 

 stream, while doubtless existing, is invisible through the absence of granular 

 particles, or, as likewise intimated by the same investigator, the two streams are 

 probably not coexistent, the returning or food-laden centripetal stream setting in 

 independently subsequent to the suspension of the invisible outflowing or centrifugal 

 one. This continuous centripetal current exhibited by the Acinetan during the 

 act of ingestion, is finally, by the above interpretation, likened to the simple 

 inflowing stream generated by a Foraminifer when withdrawing the entire mass of 

 its greatly extended pseudopodium into the substance of its body. The effort made 

 by Maupas to reconcile the anomaly in structure and function that seemingly 

 subsists between the suctorial tentacles as represented by such distinct types as 

 Hciniophrya gcmmipara and Sph(zrophrya ?nagna — these in the first-named form 

 being distinctly tubular, and, as so far reported, literally suctorial, and in the second 

 case solid and bringing about the ingestion of food-matter through the circulatory 

 movements of its central core — appears to be scarcely needed. The author is of 

 opinion, indeed, that the interpretation arrived at by this investigator in connection 

 with Sphcerophrya magna is also applicable to Hcviiophya and its allies, the 

 functional and structural properties and characters not diftering absolutely in kind, 

 but only in degree. It may thus in the first instance be submitted that the 

 more solid contents of Hemicp/irya, with its central canal, is as fully en rapport with 

 the endoplasmic substance of the body as that of the Sp/icercphrya, the diff'erence 

 alone being that whereas this sarcode matter in the last-named type is retained 

 permanently within the soft-walled tentacle as a rod-like central core, in the other 

 form, except when the animalcule is feeding, it is entirely withdrawn into the 

 substance of the body, leaving the relatively indurated walls of the tentacle standing 

 apart with a distinct central canal or lumen. The phenomena attending the 

 ingestive process would under the circumstances premised be precisely identical, with 

 the slight difference that while in the Sphcerophrya the sarcode is continuous from 

 the body to the orifice of the soft-walled tube, and available for the immediate 

 invasion and assimilation of the protoplasmic contents of the captured prey, in the 

 Hemiophrya it, under ordinary conditions, remains inert at the base of the tentacle, 

 and has to be projected through its axial cavity before placing itself in communica- 

 tion with its food. 



