178 GENERAL HISTORY OF THE INFUSORIA. 



at first closely attached to the primordial-cell, but became gradually enlarged 

 by absorption of water into a colouiiess enveloping vesicle (figs. 50, 54), 

 usually globular but sometimes oval, having two openings, thi'ough which the 

 ciha penetrate. In this condition they attain a diameter of 0-017-0-022'", 

 and are not distinguishable from encysted forms of Chlamydococcus plu- 

 vialis. Other zoospores, produced on the 1st of April, 1857, attained a larger 

 size ; and the protoplasm of the primordial cell, instead of retaining its con- 

 tinuous outline, became elongated here and there into simple or forked muci- 

 laginous rays, which were either colourless or green from the presence of 

 chlorophyll (fig. 53). These rays are probably produced by the protoplasm 

 adhering at certain points to the surrounding membrane, and being carried 

 outwards by its growth. 



The Chlamydococcus-]ike form only lasted a few hours : towards the even- 

 ing the zoospores mostly began to divide. In the first place, the protoplasmic 

 rays are di^awn in, and the primordial cell becomes roimd ; it then elongates 

 itself in the direction of an axis passing through the point of origin of the 

 ciha, and by the process of division assumes the forms shown in figs. 54 and 

 55. This state is usually attained by about nine o'clock in the evening ; and 

 about eleven o'clock a constriction commences in a plane at right angles to 

 the former plane of division ; and eventually the primordial cell is divided into 

 quadi\ints, each containing a nucleus and a portion of the red substance. The 

 two cilia, which have retained their activity, originate in the interspace be- 

 tween two quadi^ants. About midnight usually, but sometimes earlier, con- 

 striction recommences, and the form in fig. 56 is attained. This constriction 

 proceeds towards the middle point of the spheroid, by which the quadrants are 

 bisected, and ultimately divided into eight wedge-shaped portions, whose con- 

 tour-hnes, like the spokes of a wheel, meet in the middle. 



" And now commences a further process of development, which forms the 

 ground of the generic distinction between Stephanosplicera and Chlamydo- 

 coccus. For, whilst in Chlamydococcus the indi\4dual portions of a piimor- 

 dial cell separate entirely from one another, each developing its own enveloping 

 membrane, and ultimately escaping as a unicellular individual, in Stephano- 

 sphceyxt, on the other hand, the eight portions remain united as a family. The 

 coloured contents of the individual portions become drawn back towards the 

 periphery in a centrifugal direction, a colourless plasma remaining about the 

 central point ; this disappears at first in the centre ; a cavity is formed in the 

 middle of the disk ; and as this enlarges, the eight portions assume the foim of 

 a wreath, consisting of eight globular or ellipsoidal bodies in close contact 

 (fig. 57), and usually not exactly in one plane, owing to the outer membrane 

 not having expanded in proportion to the enlargement of the plasma. The 

 original cilia continue active, causing the motion of the whole organism, until 

 the eight portions are completely individualized ; and then their motion ceases : 

 but at this period each of the eight parts may be seen to be provided with two 

 ciha, which are in motion so far as their limited space allows. 



The separate parts of the plasma now form eight independent but closely- 

 packed membraneless primordial ceUs. Shortly afterwards it is seen that a 

 delicate membrane, common to them all, has been secreted beneath the mo- 

 ther-cell membrane, round the disk formed by the primordial cells ; this 

 membrane at first lies in close contact with the latter cells, foUovving the 

 constrictions of the disk, but afterwards becomes further and further re- 

 moved as it swells and tends to assume a globidar form (fig. 58), By the 

 motion of the cilia the mother- cell membrane is gradually thrown ofif, and the 

 young family escapes into the water. Its eight green primordial cells still 

 enclose the last traces of the red substance, which gradually disappears, and 



