110 Miscellaneous. 
ciliated, whereby an active movement is imparted to the intestinal 
contents. 
The oral opening, which is not quite terminal in position, is over- 
topped by one cell in front. The cirri, which I have previously 
mentioned, are borne upon this cell, as well as upon the others sur- 
rounding the mouth. These cells are therefore well differentiated 
from the remainder, so that altogether we have to distinguish three 
ditferent kinds of cells. 
The limits of each individual cell are distinctly visible, and almost 
in the centre of each there is a large roundish nucleus, containing 
several smaller nucleoli, which may usually be made out even in 
the living animal. ‘The remainder of the contents of the cell are of 
a finely granular nature, though it is impossible to determine with 
certainty whether the nutritive contents of the intestine are received 
into the cells in solid form. I am inclined to believe that this is 
not the case. A few globules of fat, on the other hand, are dis- 
cernible in most of the cells. 
I frequently found these animals of different sizes. Growth 
simply results from the reduplication of cells by division, which 
takes place in such a way that the nucleus first becomes more homo- 
geneous, since the nucleoli disappear from view. The nucleus, 
which has become elongated, then constricts, as does also the cell 
almost at the same time, whereupon complete division ensues, the 
nuclei first separating from one another and then assuming a 
rounded form. ‘They subsequently become clear again and exhibit 
the nucleoli. Whether during this apparently direct division of the 
nucleus morphological changes take place in its interior it was 
impossible to determine in living specimens. Similarly it has not 
yet been possible to decide whether a true nuclear membrane is 
present, and, if so, how it behaves during the division. At all 
eveuts, in observing the process no change can be detected at the 
margin of the nucleus. 
Unfortunately I have not yet succeeded in killing the animals 
successfully, as on the addition of foreign matters they at once 
melt away exactly like Infusoria, since the cells separate from one 
another, assuming a spherical shape, and then flatten out after losing 
their cilia. 
With regard to reproduction, two methods appear to exist. In 
the first place, in large individuals, a transverse division takes place, 
which vividly recalls the similar process in Catenula &c. The cells 
of the middle region usually first divide ; a constriction of the animal 
then sets in at this spot at right angles to the longitudinal axis, 
while a new mouth is formed in the posterior division, since a few 
cells upon the ventral surface separate from one another and give 
rise to an opening, at the same time producing stronger cilia. Upon 
this the whole is constricted off, and the two animals are set free 
and swim away. 
Besides this, however, we find conjugation, with subsequent 
encystment. ‘Two individuals apply themselves together by their 
ventral surfaces, and discontinue the movement of their cilia. They 
then become shortened and rounded into a common spherical mass, 
