Amitosis in tlie Ovary of Protenor belfragei and a Study of the Chromat in Nucleolus. 205 
two nucleoli very unequal in size and this condition is again seen in 
photos 52 and 54, and in plate XVII, photos 33 and 34. In most of the nuclei 
of photo 48, plate XVII, the nucleolus as such has disappeared and has 
cvidently given rise to the single large, dense chromosome seen in sonie 
of these nuclei. This stage is further demonstrated in photos 49 and 50, 
and photo 56 gives ahnost a complete demonstration of the origin of a 
chromatin thread from the nucleolus of the earlier stage. In the left 
nucleus of this photo the nucleolus is still intact, whereas in the right 
nucleus it is breaking down and at least contributing to the formation 
of the dense chromatin thread, from which we beüeve the two large chro- 
mosomes are formed. Photo 57 shows a group of female chromosomes 
in which the two largest chromosomes are clearly demonstrated. If the 
above described photographs demonstrate that the first step in the for- 
mation of a group of chromosomes is the Segregation of part of the diffused 
chromatin into a chromatin nucleolus, we are perhaps justified in inter- 
preting similar nucleoli, wherever found, as indicating the first differen- 
tiation of a nucleus in which will develop later the chromatic reticulum 
or spireme, characteristic of the more mature nucleus. 
With this in view it is interesting to note that in many of the large 
nuclei of zone B, the only differentiation we find is a number of nucleoli 
and further we find consecutive stages in the development of such nuclear 
masses, culminating in a syncytium of nuclei, each with its nucleolus. 
These certainly appear to be merely a further development of those early 
stages in which the presence of nucleoli is the sole indication that individual 
nuclei are being formed. Three cells from such a syncytium are shown 
in plate XVII, photo 44, and photos 45, 46, 47 and 48 are later stages 
from similar groups of nuclei, in wdiich cell walls are rarely seen. 
The evidence in Protenor Supports Will’s conclusion that the large 
nuclei at the base of zone B either fragment into smaller pieces, which 
later become differentiated into individual nuclei (plate XVI, photo 25) 
or that the smaller nuclei develop further before being set free. That the 
later stages demonstrate that the two large chromosomes may be evolved 
from the nucleolus of the earlier stage, justifies us in interpreting the 
multiple nucleoli often found in the large nuclei as evidence that such 
nuclear masses may give rise to a number of small nuclei without the 
aid of mitosis. 
We by no means wish to imply that all the large nuclei of zone B 
give rise to small nuclei, on the contrary, they frequently behave as a 
single nucleus and in such cases they may contain a single nucleolus 
(plate XIV, photos 5 and 6). They may also give rise to a single group 
