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Katharine Foot and E. C. Strobell 
of very large chromosomes either in the reduced number, (plate XV, 
photo 12) or the somatic number (plate XV, photos 13 and 14). Typical 
spireme prophases are also found (plate XIV, photos 9 and 10, and plate XV, 
plioto 11), though we have no satisfactory evidence of the mitotic division 
of such groups of very large chromosomes. But the fact that such typical 
metaphase groups are found would seem to offer sufficient evidence 
that these nuclei may sometimes divide by mitosis as well as amitosis. 
Preusse (1905) records one case of mitosis among these cells and botli 
Giardina 1901 and Günthert (1910) demonstratc mitotic divi ion of 
K ährzellen. 
If the presence of mitosis among these cells can be questioned, no 
such doubt exists as to amitosis, for it is impossible to ignore its frequent 
occurrenee, not only can fragmentation of these cells be demonstrated 
but they may also show the typical amitotic division so frequently dc- 
scribed for other forms. The nucleolus frequently divides first though 
this is by no means constant. Photos 5 and 6, plate XIV, show two large 
nuclei with the nucleolus still undivided. Photo 19, plate XV is a cell 
witli the nucleolar mass divided and the nucleus sliowing the first indi- 
cati'on of elongation and constriction. Photo 20 shows a further con- 
striction of the nucleus. Photos 7 and 8, plate XIV show two of the large 
nuclei with division almost completed. Photos 20 — 24, plate XV give 
some indication of the great variability shown by these nuclei in their 
method of division. We would call attention to the fact that in all these 
cases a portion of the cliromatin is segregated either into a nucleolar- 
like mass (photos 5, 6, 7 and 8, plate XIV, photos 19, 22 and 23, plate XV) 
or the segregating chromatin may form a spireme (photos 9 and 10, 
plate XIV, photos 11, 21 and 24, plate XV). It would seem that apparently 
the same substance may in one case form a nucleolus and in another may 
be transformed directly into a spireme and chromosomes, and this woiüd 
seem to question the view that the substance which forms the chromo- 
somes and nucleolus is fundamentally different, it suggests rather that 
the evidence given by mere morphological differences does not offer a 
trustworthy clue to fundamental causes. 
Chromatin Nucleolus. 
Montgomery (1901) was the first to demonstratc the chromatm 
nucleolus in the spermatogcnesis of Protenor. It is the “X-element” of 
his earlier papers and he describes it as follows: “This element has a 
remarkable history in the growth period. Through the whole growtli 
