914 THE ANIMAL KINGDOM. 



passes readily into a quiescent encysted stage. The cells then enlarge, 

 turn more granular, and display a more pronounced tint ; finally they 

 become ovate and -035 mm. long. Each of them secretes a smooth thick 

 membrane, whilst the matrix becomes firm and superficially granular. If 

 such an encysted mass is placed in water each cell in about six weeks' time 

 divides into four parts, which are set free as motionless globular cells by 

 the gradual absorption of the cyst-membrane. The cells appear to 

 change into spindles which, whether single or in masses, produce fila- 

 mentary tracks along which they move 1 . 



Chlamydomyxa like Labyrinthula has a resting and a motile phase. 

 It has, however, in the former condition the power of growing. The 

 smallest encysted examples have the form of minute spherical bodies of a 

 green colour, with or without a red granule, inclosed by a delicate cellulose 

 membrane. Such bodies occur free when they grow for some time 

 without losing their spherical shape, or else lodged within the cells of, 

 e. g. a Sphagnum leaf. In this case they elongate, but at last force their 

 way outwards to the surface of the leaf where they protrude. The protrusion 

 increases in size by degrees, and finally the protoplasm may be withdrawn 

 entirely from the portion of the cyst which remains within the leaf. 

 During growth fresh laminae of cellulose are continually laid down within 

 the membrane first formed. Encysted examples with the structures 

 described are most variable in shape. The contents of a cyst may divide 

 into equal or unequal parts, everyone of which surrounds itself with a 

 cellulose membrane. The number of red granules increases, and it not 

 infrequently happens that some of them become inclosed within layers of 

 cellulose producing internal wart-like growths. In some instances the cysts 

 acquire a ruddy hue. The motile condition has been seen only by Archer. 

 The envelopes of the cyst burst at some one point, its contents push forth a 

 stem which branches and spreads, the branches in turn giving origin to 

 delicate, widely-extended, and ramified filamentary tracks. The last- 

 named, though flexible, do not change their shape or do so but slowly. 

 The contents of the ruptured cyst are, according to Archer, a hyaline 

 protoplasm with an amorphous greenish substance, yellow-green granules, 

 red granules, and great number of pale-blue globules. There is no 

 nucleus but the stem and its branches possess a number of contractile 

 vacuoles. The pale-blue and non-nucleated globules transform themselves 

 into spindles which wander along the tracks ; they change their shape 

 when they reach a point where a track bifurcates. Their motion may 

 cease or become retrograde, and they may, as in Labyrinthula^ collect 

 in outlying masses. The whole structure, tracks, spindles, branches, and 

 stem may be withdrawn into the cyst ; and it may happen that outlying 



1 Brandt has suggested that the yellow cells of the Radiolarian Acanthometra tetracopa are 

 identical with the spindles of L. vitellina-, Mitth. Zool. Stat. Naples, iv. 1883, p. 239. 



