ZOOLOGY; KOFOID AND SWEZY 
13 
t3rpically and solely flagellate in their occurrence. Nothing comparable is 
known to occur in the ciliates in which at mitosis the cilia bear no morpho- 
logical relation to the centrosomes or to any other part of the mitotic figure. 
In the group of flagellates comprised in the order Polymastigina, the para- 
desmose is a characteristic feature of mitosis in so far as these processes have 
been studied. In the trichomonad flagellates, as pointed out above, its 
occurrence is constant and characteristic. In the nearly related form, 
Hexamitus, the paradesmose is also present.^ A peculiar development of this 
structure is found in the so-called sphere of Noctiluca. This is produced by 
the elongation and division of a mass of differentiated archoplasm outside 
the nucleus. The exact relation of this to the tentacle and flagellum of 
Noctiluca has not been determined, but its position would suggest that some 
close connection between them exists. 
It has been pointed out in our earlier paper"^ on trichomonad flagellates 
that the paradesmose is not a precise homologue of the centrodesmose or cen- 
tral spindle of the metazoan type of mitosis. It is the result of two peculiar 
specializations in trichomonad division, the continuity of the nuclear mem- 
brane which excludes it from the typically axial position of the central spindle, 
and the connection of the centrosome-blepharoplast with the entire motor 
organelle complex. The latter feature is probably the most important one in 
its bearing on the development of the paradesmose, the strain on the spindle 
resulting from the constant activity of a group of flagella attached to each 
pole, requiring the development of a stronger support than is found in the 
mitotic structures where this condition does not prevail. As a result of this 
necessity we find a paradesmose developed in those flagellates where the 
flagella form part of the mitotic figure, but it is usually, if not always, absent 
where this does not occur. 
In no other group of Protozoa do we find a structure approximating the 
paradesmose of the flagellates. Among the ciliates division of the nucleus 
occurs as distinct phenomena separated from, though synchronous with, 
the division of the motor organelles and other structures of the body. 
Another point in the division process of Trichonympha which is equally 
important as those mentioned above, is the fact that division is longitudinal. 
This is shown in the longitudinal splitting of the centroblepharoplast and the 
ectoplasmic structures. This fact also serves to separate it from the ciliates 
where transverse division is general, and allies it with the flagellates. 
The occurrence of these peculiar flagellate specializations in Trichonympha 
would therefore preclude the possibility of any ciliate affinities for that genus. 
This conclusion receives confirmation from a careful analysis of its morpho- 
logical features which, though superficially ciliate in appearance, yet are 
fundamentally flagellate in their character and relationships. 
The relations of other members of the group of curious and peculiar organ- 
isms which, in company with Trichonympha, are parasitic in the intestinal 
