CELL-DIVISION IN THE SEX CELLS OF TAENIA 215 
5. Cleavages 
Since fertilization has not been considered the relation of the 
two pronuclei previous to the first cleavage spindle has not been 
observed. In Taenia, Richards describes cleavage as taking 
place by mitotic division. In Moniezia, he finds frequent mitoses 
and no facts which he is able to interpret as amitosis. Child 
says, in his earlier paper, that in Moniezia the first cleavage is. 
usually or always mitotic but cases of mitotic divisions are 
rarely seen after the first cleavage. He finds what he interprets 
as frequent cases of amitosis. In his later paper he says that 
mitosis occurs much later than the first cleavage but that the 
prevailing method of segmentation is by amitotic division. 
a. Character of the cleavage. In Taenia, I find frequent cases 
of mitosis, not only in first segmentation but also in later seg- 
mentations. In fact, there are very few sections in my material 
where segmentation is taking place which do not have evidences. 
of mitotic figures. The figures of mitosis that I have shown in 
plates 4, 5 and 7 might be duplicated many times. In Taenia 
teniaeformis it is not a question of whether mitosis occurs in 
some stages of segmentation and not in others, nor is it a ques- 
tion as to the frequency of its occurrence. The question is, 
whether or not mitosis is the only method of segmentation. The 
figures of plate 6 are essentially similar to Child’s figures of ami- 
totic division. I find these figures about as numerous as those 
which are unquestionably mitosis. These conditions occur, not 
only in later segmentations, but in early segmentation and many 
that I have figured are taken from first and second segmenta- 
tions. The question is, do these admit of any interpretation 
other than that the nucleus has divided amitotically? I will 
discuss this question later. 
In cleavage, nuclear division takes place very much in advance 
of cytoplasmic division. In the early divisions it is the exception 
and not the rule to find even a constriction in the cytoplasm. 
This gives rise to a syncytial condition. This syncytium per- 
sists until very late cleavage. Richards says that, in properly 
fixed material, he has never seen an egg syncytium. It cannot 
be the lack of proper fixation or stain which gives this syncytial 
