954 D. WARD CUTLER 
found in Joenopsis polytricha. Just beneath the 
surface of these ridges numerous granules are located, from 
each one of which a body flagellum has its origin (PI. 10, figs. 1, 
4, 6, s.n., B.G.). The flagella origins are in the main similar 
to those described by Kofoid and Swezy in I. campanula 
and Leidyopsis sphaerica, except that I can find no 
trace of oblique fibres running to the granules. 
Nucleus. 
This body is a large structure situated at the anterior end 
of the body and possessing a well-developed membrane, always 
. 
Trxt-ric. 1. TEXT-FIG. 2. 
-__— 
‘ Resting ’ nucleus of P. pristina Similar to Text-fig. 1, but show- 
showing chromatin blocks em- ing the tripartite nucleolus- 
bedded in the plastin matrix. Note like body. x 1,800; s.A.,D.H. 
the clear peripheral space with the 
nucleolus-like body. x 1,880;s.a., 
H.1.H.1 
clearly visible (Pl. 10, figs. 1, 8, and Text-fig. 1). Inside the 
membrane there is constantly present a clear space, while 
the centre of the nucleus 1s filled with chromatin, in the form 
of large irregularly-shaped masses lying in a matrix of what is 
probably plastm. The number of chromatin blocks appear 
to be quite indefinite (‘Text-figs. 1 and 2, ¢.B.). Lying amongst 
them there is commonly seen a large body, staimimg very 
deeply with iron haematoxylin, which is sometimes distinctly 
tripartite in nature (Text-fig. 2, N.). Unfortunately [have been 
' For explanation of lettering of text-figures see pp. 263-4. 
