216 
Katharine Foot and E. C. Strobell 
formed we have rare cases in which a large chromatic nucleolus is breaking 
up and the cliromosomes apparently emerging from this nucleolus. We 
have several photographs showing this condition but as these nucleoli 
are iuuch larger than typical and the chromatin shows other atypical 
features, we concluded they were not normal. We now believe such 
cases are in keeping with what is known of the great variability of nu- 
cleoli and should not be set aside as abnormal. 
We have found nothing in the germinal vesicles of Protenor which 
can be homologized to either the large or the small nucleolus of Allo- 
lobophora foetida and further there is a lack of agreement in the earlier 
development of the oöcvtes. Photos 62 — 72 (which mav be interpreted 
as stages prior to the great growth period) are quite different from the 
corresponding period of development in Allohbophora and indicate what 
has been so often suggested — that it is not safe to assume that in the 
development of the cell the same results must alwavs be achieved through 
the same morphologicai expressions. 
It is an interesting fact that in Protenor the chromatin nucleolus is 
not present in the female at the stage at which it is present in the male 
and on the other hand it is present in the female at the stage at which 
it is claimed it is absent in the male. Montgomery (1901) found that 
the chromatin nucleolus (X-element) is not present in the spermatogonia — 
first appearing in the spermatoevtes — and his conclusions on this point 
have not been questioned by subsequent workers on this form (Wilson 
1906 and Morrill 1910). 
In accord with Morrill we find that the chromatin nucleolus is not 
present in the oöcvtes at the stages in which it is so pronounced in the 
spermatoevtes but we have demonstrated further that it is present in the 
ovarian cells at the stages in which it is claimed it is absent in the male. 
It must be coneeded that the evidence that the ovarian nucleolus 
frequently gives rise to the two large cliromosomes of the female and that 
the large chromosome of the spermatocytes arises from a similar nucleolus 
are facts which seem to show a dose relation between the so-called sex 
determining cliromosomes. We ought however to find this same relation 
between the so-called sex cliromosomes in other forms if the evidence is 
to be considered of much value but we have been unable to demonstrate 
a similar ovarian chromatin nucleolus in either Anasa or Euschistus though 
we have used exactly the same methods 1 ). Further there is evidence in 
*) In stetions, one, two ortliree nucleolar structures are frequently present, and 
-are about equal in size, but if auy if tlicse are identical with the ovarian nucleolus. 
It seems reasonable to expect that they would be demonstrated by the same technique. 
