210 M. M. Mercatr 
The structure of Opalina and the phenomena of mitosis. 
In the description of the structure of Opalina, I will begin for 
each organ with the conditions in OQ. itestinalis and will then com- 
pare with the other species studied. 
Cilia. 
I have little to add to or to modify in Marer’s (1903) dis- 
cription of the cilia in Opalina ranarum. In all species studied the 
conditions of the cilia are similar. It is easy to cause the dis- 
integration of specimens of O. intestinalis and O. caudata by pressing 
intermittently upon the cover-glass above them. One then sees many 
of the cilia, with their basal granules attached, floating freely inthe 
salt solution. Occasionally such isolated cilia may show a few 
faint contractions after their complete separation from the body. 
Similar phenomena have been observed in ciliated cells by KuEss (1888), 
Biscuit (1885 a), Fiscoer (1895) and Pretrer (1899), and for the iso- 
lated tails of spermatozoa by numerous students (cf. MevEs 1899 6). 
In tangential sections of the body of any species of Opalina, 
one sees a network of fibres beneath the pellicula (Fig. 2). The 
spiral-longitudinal rows of basal granules le just below the larger 
fibrils, the course of the two exactly coinciding. The much more 
delicate transverse fibrils stretch between the longitudinal fibrils, 
each end coinciding in position with a basal granule. In this regard 
it is seen that my study confirms TdnnicEs (1898) rather than 
Mater (1903). The observation of contraction in isolated cilia shows 
that their movements are automatic, as Marer claims in opposition 
to ToOnniGEs, but it seems probable that the coordination of the 
movements of the cilia may be connected with the presence of this 
network. The transverse fibrils of this network lie beneath and not 
in the pellicula, as accurate focussing clearly shows. The longitudinal 
fibrils are a little more superficial, lying apparently at the level of 
the outer ends of the basal granules. 
Nether O. intestinalis nor O. caudata have any tuft of longer cilia 
at the anterior end of the body, such as Licrr & Dusosca (1904 d) 
discribe for O. saturnalis. In O. saturnalis the anterior tuft of cilia 
is not very distinct from the adjacent cilia. 
There is no posterior zone, as in O. saturnalis, from vas the 
cilia are absent. | 
