166 GENERAL HISTORY OF THE INFUSORIA. 



cells stand, is regarded as the equator of the envelope-cell, we ordinarily 

 find their position such that the equatorial zone lies parallel with the plane 

 of the object-glass, and the observer consequently looks down upon the pole 

 of the envelope-cell. In this, the jpolar view, the eight primordial cells 

 stand in a perfect cii'cle and are placed very close to the circumference of the 

 envelope-cell. The distances between the primordial cells are more or less 

 considerable according as they are proportionately larger or smaller ; some- 

 times they constitute an elegant wreath composed of eight large green rosettes, 

 almost without any intervals between them, or resemble an interrupted eight- 

 angled star ; sometimes the green globules are so far apart as to look like the 

 eight spokes of a wheel. The diameter of a primordial cell in the polar view 

 amounts in the former case to y^th of a line (0-012 mm.), in the latter to 

 ^th (0-0065),— on an average to ^th of a line (0-0087 mm.). 



" When, however, the whole revolves, so that the axis passing through the 

 two poles of the envelope-cell lies parallel with the stage of the microscope, 

 and the equatorial zone marked by the eight green primordial cells stands 

 perpendicular to the latter, consequently in the optic axis of the microscope, 

 the envelope-cell still looks like a circle, because it is a sphere ; but the eight 

 primordial coUs, lying in one plane, are then projected in a line which corre- 

 sponds to the diameter of this circle, so that the whole resembles, under the 

 microscope, a colourless disk cut in half by a green zone (XIX. 40-58). And 

 in this, the eqaatorial view, according to the position, the foiu' primordial 

 cells in the anterior hemisphere sometimes completely cover the four behind, 

 so that only four are seen altogether ; sometimes the latter appear through 

 the interspaces between the former, and all eight are seen in one line. This 

 view also, of course, gives very different pictures according to the size of the 

 primordial cells and the distance between them. 



" Between the polar and equatorial views lie countless intermediate posi- 

 tions in which the ring of primordial cells, more or less contracted, appears 

 as an ellipse, with its longest axis constantly in the diameter of the envelope- 

 cell, while the shorter axis appears longer or shorter, and the separate pri- 

 mordial cells are approached more or less towards each other, according to the 

 laws of projection. 



*' Besides this diiference of the aspect Avhich one and the same individual 

 affords merely in consequence of the different i^ositions resulting from its 

 movements, a still greater variation is displayed in the sha2:)e of the green 

 primordial cells themselves. 1 have called them globes above ; properly they 

 are always acuminated to some extent, in the form of a pear, toward the 

 periphery of the envelope-cell ; and they are imperceptibly attenuated to a 

 point here, from which two cilia pass out (XIX. 38). These cilia therefore 

 arise from the primordial cells inside the envelope-cell, and they emerge freely 

 into the water through minute orifices in the latter : from the analogy with 

 Chlamydococcus, I conjecture that there is a separate passage for each cilium, 

 so that the orifices corresponding in each case to the primordial cells are 

 placed in pairs, and all sixteen orifices occur in the equator of the envelope- 

 cell. Hence in the polar view the eight pairs of cilia go out from the cii'cum- 

 fcrence of the envelope-ceU like elongated rays. 



" The primordial cells moreover expand principally in the direction of ike 

 axis perpendicular to the equatorial plane, so that in the equatorial view they 

 appear not spherical, but rather elliptical, or even sometimes stretched so 

 considerably in this direction, that they become cylindi-ical or almost spindle- 

 shaped, without undergomg any remarkable enlargement on the other axis. 

 If in this case the primordial cells are large and near together, they form 

 in the equatorial view a broad green zone inside the colomless envelope- 



