ZOOLOGY: KOFOID AND SWEZY 
9 
FLAGELLATE AFFINITIES OF TRICHONYMFHA 
By Charles Atwood Kofoid and Olive Swezy 
Zoological Laboratory, University of California 
Communicated by W. M. Wheeler, November 13, 1918 
The methods of division among the Protozoa are of fundamental signifi- 
cance from an evolutionary standpoint. Unlike the Metazoa which present, 
as a whole, only minor variations in this process in the different taxonomic 
groups and in the many different types of cells in the body, the Protozoa have 
evolved many and widely diverse types of mitotic phenomena, which are 
characteristic of the groups into which the phylum is divided. Some strik- 
ing confirmation of the value of this as a clue to relationships has been found 
in recent work along these lines. The genus Trichonympha has, since its 
discovery in 1877 by Leidy,^ been placed, on the one hand, in the cilia tes 
and, on the other, in the flagellates, and of late in an intermediate position 
between these two classes, by different investigators. Certain points in its 
structure would seem to justify each of these assignments. A more critical 
study of its morphology and especially of its methods of division, however, 
definitely place it in the flagellates near the Polymastigina. 
At first glance Trichonympha would undoubtedly be called a ciliate. The 
body is covered for about two- thirds of its surface with a thick coating of 
cilia or flagella of varying lengths, which stream out behind the body. It 
also has a thick, highly differentiated ectoplasm which contains an alveolar 
layer as well as a complex system of myonemes. The nucleus, however, is 
that of a typical flagellate. The flagella may equally well be called cilia, 
since they are arranged in longitudinal rows on the surface of the body, each 
arising from a minute basal granule imbedded in the ectoplasmic layer. Each 
basal granule, however, is connected with a fine fibril arising from the myo- 
nemes in the ectoplasm. The myonemes form a closely anastomosing net- 
work over the body, taking their origin from a complex structure at the 
anterior end which we call the centroblepharoplast (fig. 1, c). This corre- 
sponds to the blepharoplast of Trichomonas (fig. 6, c). The entire group of 
flagella are thus bound together into one integrated unit, the basis of which is 
the centroblepharoplast, forming the neuromotor system. 
This integrated organelle system is found in a simple form in Trichomonas 
(fig. 6) where it consists of a centrosome-blepharoplast (c) imbedded in the 
anterior end of the axostyle (ax) . From it arise the flagella and the undulat- 
ing membrane with its marginal filament and parabasal body. 
A more complex form of the same system and one which in some features 
leads toward the stage attained by Trichonympha with its much greater 
multiplicity of flagella, is shown in the motor organelle complex of Giardia} 
