CELL-DIVISION IN THE SEX CELLS OF TAENIA 214 
The Ringer’s solution was put into an open vessel in an open 
paraffin oven. By means of a Bunsen burner the oven was kept 
at such a temperature that the Ringer’s solution was 39°C. As 
soon as the host was killed, the tape worms were taken from the 
intestine and transferred to the Ringer’s solution. Immediately 
a proglottid from that portion of the worm which, in accordance 
with my former observations, contained segmenting ova, was 
transferred to a slide on a constant temperature stage which 
had previously been heated to 39°C. Here the proglottid was 
opened and some of the ova were teased out in the Ringer’s 
solution and covered with a cover-glass. To prevent rapid 
evaporation the cover-glass was sealed with a ring of vaseline. 
Besides preventing evaporation the vaseline supported the cover- 
glass. The first preparation was observed two hours with a 
4 mm. objective and a Zeiss 12 compensating ocular. Other 
slides were prepared in a similar manner and observed for differ- 
ent lengths of time, varying from ten minutes to three hours. 
Typical resting nuclei were seen, but in no case could there be 
determined any indication of cell-division or even a slight con- 
striction in the form of the nucleus. Frequently the cells col- 
lected in groups, usually of twos but sometimes more than two 
’ cells were in a group. At first sight these groups of cells might 
have been mistaken for constricting cells but closer observation 
revealed that they were not cells in the process of constriction 
but merely cell groups, or more exactly speaking, groups of ova, 
for it was possible to distinguish two and even three nuclei in a 
single ovum. 
To make sure that cell-division was taking place in the worms, 
this experiment was repeated about a week later and pieces of 
the worm upon which the experiment was being made were killed 
in Flemming’s strong solution. The results of the observations 
on the live material were the same as in the first experiment but 
when the fixed material was sectioned it showed mitotic division. 
Soon after the above experiments were made there appeared 
an article by Morse (711) in which he reports similar results. In 
his experiments, which were upon Calliobothrium and Crosso- 
bothrium, he used the plasma of the host asa medium. Although 
