Amitosis in the Ovary of Protenor belfragei and a Study of the Chromatin Nucleolus. 217 
Protenor that sometimes all the chromosomes may arise from a chromatin 
nucleolus (plate XIV, photos 5 to 10, and plate XV, photos 11 — 14). 
Again the presence of amitosis in this form certainly weakens if it does 
not cancel any evidence we find that might be claimod as a Support of 
the continuity hypothesis. 
Chromosomes. 
In the few forms we have studied we have found enough variability 
in the size, number and form of the chromosomes to make us skeptical 
of all theories which involve a belief in their individuality and continuity. 
We do not question and have never questioned the observations of the 
investigators who have recognized definite forms and definite behavior 
of certain chromosomes; but we have questioned that such forms and 
such behavior have enough constancy to justify the far-reaching generali- 
zations which have been based upon them. 
Of the presence of rings and crosses in AHolobopliora foetida (1905) 
we stated: “We find no constant form differences of the chromosomes . . . 
These present a variety of shapes-rings, figures 8, crosses etc. without 
any regularity or constancy ... In some cases all the eleven chromo- 
somes are rings and sometimes not a single ring is found.” In Anasa 
tristis (1907) we found similar irregularities — for example the cross 
form is not always associated with a definite chromosome, though “there 
is a frequent repetition of certain forms”. As the to size relations, “We 
constantly find a Variation in the relative size of entire bivalents, such 
variations making size relations of a chromosome a most uncertain guide 
for identification, unless the difference in size is so extreme it allows for 
individual Variation.” 
In Euschistus variolarius (1909) we found similar variations — it is 
“possible to select chromosome groups which exactly fit a given theory; 
but many groups can also be found that are a serious menace to these 
theories, while on the other hand they present no difficulties to the con- 
ception of those who regard the number, size and form of the chromosomes 
as inherited characters — the expression of cell activities rather than 
the cause.” 
In Protenor similar variations exist as shown by a comparison of 
the few chromosome groups demonstrated in this paper. In the 
bivalent chromosome groups of photos 85, 86, 87 and 88, plate XX, 
one and sometimes two of the chromosomes are in the form of a 
cross; but this form is not always associated with the same chromo- 
Archiv f. Zellforschung. VII 15 
