PROTOZOA 



15 



of the network appear to consist of contractile protoplasm, whilst 

 m the latter they are described as firm homy threads exuded by 

 the spindle-cells. Neither form has been re-examined since its 

 discovery ; and it is possible that this apparent difference will be 

 removed by further study. 



Era. VII.— Hellozoa. l. Aotinophrys tol, Ehrb. ; x 800. a. food-particle 

 lying in a large food-vacuole ; 6, deep-lying finely granular protoplasm ; e, 

 axial filament of a paeudopodium extended inwards to the nucleus ; d, the 

 central nucleus; e, contractile vacuole; /, superficial much-vacuolated 

 protoplasm. 2. Clathrulina elegans, Cienk. ; x 200. 3. Heter- 



ophils marina, H. and L. x 660. a, nucleus ; b, clearer protoplasm 

 surrounding the nucleus ; c, the peculiar felted envelope. 4. EwpM- 



diophrys pallida, F. B. Sohultze ; x 430. a, food-particle ; 6, the nucleus; 

 c, contractile vacuole ; d, central granule in which all the axis-filaments of 

 the pseudopodia meet. The tangentially disposed spicules are seen 

 arranged in masses on the surface. 5. Acanthocystis turfacea, Carter ; 



X 240. a, probably the central nucleus ; h, clear protoplasm around the 

 nucleus ; c, more superficial protoplasm with vacuoles and chlorophyll 

 corpuscles ; d, coarser siliceous spicules ; e, finer forked siliceous spicules ; 

 /, finely granular layer of protoplasm. The long pseudopodia reaching 

 beyond the spicules are not lettered. 6. Bi-flagellate "flagellula" of 



Acantliocystis aculeata. a, nucleus. 7. Bitto of Clathrulina elegans. 



a, nucleus. 8. Astrodisculus ruier, Greeff ; x 320. a, red-coloured 



central sphere (? nucleus) ; 6, peripheral homogeneous envelope. 



Class V. HELIOZOA, Haeokel, 1866. 

 Characters. — Gymnomyxa in which the dominating amoeba phase 

 hajs the form of a spherical body from the surface of which radiate 



numerous isolated filamentous pseudopodia which exhibit very little 

 movement or change of form, except when engaged in the inception 

 of food-particles. The protoplasm of the spherical body is richly 

 vacuolated ; it may exhibit one or more contractile vacuoles and 

 either a single central nucleus or many nuclei (Nuolearia, Actino- 

 sphaerium). Skeletal products may or may not be present. Flagel- 

 lulse have been observed as the young forms of some species (Aoan- 

 thocystis, Clathrulina), but very little has been as yet ascertained 

 as to spore-formation or conjugation in this group, though isolated 

 facts of importance have been observed. Mostly freshwater forms. 



Fig. VIII.— Heliozoa, l- Actinosphaeriwm Eichhornii, Ehr. ; X 200. a, 

 nuclei ; b, deeper protoplasm with smaller vacuoles and numerous nuclei ; 



c, contractile vacuoles; d, peripheral protoplasm with larger vacuoles. 

 2. A portion of the same specimen more highly magnified and seen in 

 optical' section, a, nuclei ; b, deeper protoplasm (so-called endosarc); 



d, peripheral protoplasm (so-called ectosarc); e, pseudopodia showing the 

 granular protoplasm streaming over the stiff axial filament ; /, food- 

 particle in a food-vacuole. 3, 4. Nuclei of Actinosphseriimi in the 

 resting condition. 5-13. Successive stages in the division of a 

 nucleus of Actinosphasrium, showing fibrillation, and in 7 and 8 formation 

 of an equatorial plate of chromatin substance (after Hertwig). 14. 

 Cyst-phase of Actinonphxnwm Eichhotnii, showing the protoplasm 

 divided into twelve chlamydospores, each of which has a siliceous coat ; 

 a, nucleus of the spore ; g, gelatinous wall of the cyst ; h, siliceous coat of 

 the spore. 



