742 MICROSCOPIC FORMS OF ANIMAL LIFE PROTOZOA 



A large number of new arid curious fresh-water forms of this 

 type are being frequently brought under notice, of which the Clatlrn- 

 llna elegans (fig. 576) may be specially mentioned as presenting an 

 obvious transition to the Polycystine type. This has been found 

 in various parts of the -Continent, and also (by Mr. Archer 1 ) in 

 Wales and Ireland, occurring chiefly in dark ponds shaded by 

 trees and containing decaying leaves. Its soft sarcode-body, which 

 is not differentiated into ectosarc and endosarc, is encased by a 

 siliceous capsule of spherical form, regularly perforated with oval 

 apertures, and supported on a long silicified peduncle. The body 

 itself and the pseudopodia which it puts forth through the aper- 

 tures of the capsule seem closely to correspond with those of 

 Actinophrys. Reproduction here takes place not only by binary 

 fission, but by the formation of ' swarm-spores.' In the first mode, 

 one of the two segments remains in possession of the siliceous cap- 

 sule, whilst the other finds its way out through one of the apertures. 

 lives for some hours in a free condition as an Actinophrys, and 

 ultimately produces the capsule and stem characteristic of its type. 

 In the second mode numerous small rounded sarcode masses, cadi 

 possessing a nucleus, are produced within the capsule, in what 

 manner cannot be clearly made out ; and every one of these is 



enveloped in a firm en- 

 velope, set round with 

 short spines, probably 

 siliceous. These cysts 

 remain for months with- 

 in the common capsule ; 

 siiid when the time arrives 

 for their further develoj >- 

 meiit the sarcode-cdr- 

 puscles slip out of their 

 cysts, and escape through 

 the orifices of the capsule 

 as flagellated monads of 

 oval form (fig. 576, B), 



FIG. 577.-Diagrammatic representation of \ Amoeba eac h having a nucleus. 

 proteus: hi (J, ectosarc; Jii JN, endosarc; C V, con- ,-, , ,, , 



tractile vesicle; N, nucleus; P, pseudopodia; 

 VIL, villous tuft. 



VIL 



, 



tile 



,-, , 



near tne lmse 

 flagella, and two con- 

 tractile vesicles near its 



opposite end. After swarming for some hours in this condition, 

 they change to the free Actinophrys form, and finally acquire the 

 siliceous capsule and stem of the Clathruliiia. 



Lobosa. No example of the rhizopod type is more common in 

 streams and ponds, vegetable infusions, &c., than the Anweba 

 (fig. 577); a creature which cannot be described by its form, for 

 this is as changeable as that of the fabled Proteus, but may yet be 

 definitely characterised by peculiarities that separate it from the 

 two groups already described. The distinction between * ectosarc ' 

 and * endosarc ' is here clearly marked, so that the body approaches 



1 See his memoir on Fresh-water Radiolaria in Quart. Journ. of Microsc. Sri. 

 n.s. vol. ix. 1869, p. 250. 



