10 
ZOOLOGY: KOFOID AND SWEZY 
Here we find eight distinct fiagella arising from different points on the sur- 
face of the body, but connected internally by a number of fibers which all 
take their origin from the centroblepharoplast complex attached to the an- 
terior ends of the axostyles. The condition in Giardia differs from that in 
Trichonympha mainly in the small number of parts of its motor organelle 
complex. Correlated with the very great increase in the number of fiagella 
in the latter species, is the vast increase in the number of distinct myonemes 
which have been developed. This has also necessitated an enlargement and 
increased complexity in the centroblepharoplast complex at the anterior end 
of the body. These structures still remain, however, distinctly flagellate in 
their structural relationships, though superficially resembling the ciliary 
coating found in the holotrichous Ciliata. 
The mode of division found in Trichonympha offers still more striking proof 
of its fiagellate affinities, and also emphasizes the wide divergence existing 
between it and the ciliates. As the name signifies the centroblepharoplast 
complex takes the role of centrosome in mitosis. In the prophase this entire 
structure divides by longitudinal splitting, followed by a division of the 
ectoplasmic part of the body, including a separation of the myonemes and 
fiagella into two parts (fig. 2). As the centroblepharoplast divides the two 
moieties spin out a darkly staining band between them, the paradesmose 
{par). 
The nucleus migrates from its submedian position to the anterior part of 
the body. A precocious splitting of the chromosomes has taken place during 
the vegetative phase and the fifty-two chromosomes thus formed are re- 
united, forming twenty-six V-shaped chromosomes composed of distinct 
chromomeres (fig. 2). As the nucleus reaches the paradesmose it elongates 
until its length coincides with that of the paradesmose. The nuclear mem- 
brane remains intact throughout the entire process of division. Spindle 
fibers are formed from the ends of the paradesmose, or the centroblephara- 
plasts, pass through the nuclear membrane and become attached to the chro- 
mosomes, a fiber from one pole to one end while the other is connected with 
the opposite pole. With the shortening of the spindle fibers the chromosomes 
are straightened out in the equatorial plate stage (fig. 3). 
In all these mitotic figures the divided centroblepharoplast functions as 
the centrosome, while the myonemes, surface ridges and fiagella are found 
attached to each half and streaming out from it like the astral rays in mitosis, 
in a metazoan nucleus. The paradesmose lies above the nucleus, that is, 
towards the surface of the body, outside the nuclear membrane but partly 
enfolded within it. 
In the telophase the constriction of the nuclear membrane takes place 
with the chromosomes still showing their attachment to the spindle fibers. 
The chromosomes are never drawn close to the poles as in mitosis in Tricho- 
monas, but the fibers fade out before reconstruction begins in the nucleus 
