186 W. WALDEYER. 
(as in cells of ovary of dogs) acquires a stronger refraction and 
a greater tendency to take stains. Van Beneden is unable to 
agree with Flemming that this depends on the formation of a 
more strongly refracting outer layer. The division over they 
lose this peculiarity. 
Again, E. van Beneden (28) discovered the “ Polkorperchen ” 
and the “ sphéres attractives,” about which we must now enter 
into some detail. 
According to the recent work of van Beneden and Neyt 
(24) the “sphéres attractives ” appear very early in Ascaris 
megalocephala, at the time, indeed, when the so-called pro- 
nuclei (see below, Part II) still retain a reticular structure and 
are far apart. They appear as two areas in the protoplasm. 
at first near one another, spherical in form, and deeply staining, 
In the centre of this area lies the pole-body surrounded by 
a clear ring (van Beneden now prefers to call it the “ central 
body ”). Later on these move apart towards the poles, and 
from them there start the various streamings (radiating figures) 
which are observed in the egg-protoplasm, and at the position 
of the nucleus during the process of division. The dark part 
of the “ sphére attractive”’ is called the ‘cortical zone,”’ the 
light ring round the “ central body ” is the “ medullary zone.” 
The streaming shows itself (1) as the spindle figure, the 
polar points of which are fixed at the two central bodies; (2) 
as the cone of rays known as the ‘‘ cOne-antipode” (fig. 13), 
which lies in an inverted position with the base towards the 
periphery ; and (3) as the chief ray-figure in the protoplasm, 
the “ star figure” or aster. All these three ray-figures unite 
at the central body ; the “ céne antipode” is part of the aster, 
contrasted with it by its more marked rays; where the anti- 
podal cone touches the surface of the egg a circle is marked 
out—the “ polar circle.” Sometimes this is recognisable as a 
low ridge. A similar ridge circumscribes the star figures on each 
side of the equator, named by van Beneden the “ tropical circle” 
(‘circle subequatorial ”). Between the two tropical circles 
there remains an equatorial zone free from streaming; this 
(bourrelet équatorial) projects slightly. In this zone le the 
