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found in a paper, “The Accessory Chromosome — Sex-determinant ?”, 
the MS. of which is in the hands of the editor of the Journal of Mor- 
phology. Since it may be some time before this will be printed, I 
have thought it best to make preliminary announcement of some of 
my more important results. 
The purpose for which the original article was written may be 
gathered from the following quotation: “From these different obser- 
vations, I hope 1) to bring out the essential features which charac- 
terize the accessory chromosome, 2) to show the extreme probability 
of its universal occurrence among insects, 3) to outline its history in 
the different cell generations of the testis, and 4) to suggest a theory 
in explanation of its function.” 
Before taking up a discussion of these points, a few words re- 
garding the name to be applied to this element may not be out of 
place. HENKING, who first noted it, calls it a “nucleolus” during the 
early stages of the spermatocytes, and later a “chromatin element”. 
MONTGOMERY, who next observed it in the Hemiptera, prefers to call 
it a “chromatin nucleolus”, while PAULMIER, working upon the same 
order of insects, designates it the “small chromosome”. I, myself, 
early chose the name ‘accessory chromosome” and still consider it 
preferable to the others suggested. My reasons for this are as fol- 
lows: All observers are agreed that the element is composed of chro- 
matin and that it divides in mitosis like all other chromatin elements. 
The only essential feature wherein it differs from other chromosomes 
is that during the prophase of the first spermatocyte it fails to lose 
its identity in the spireme; and further, that during one of the sper- 
matocyte mitoses it remains undivided. 
It is therefore a chromosome and never, in any sense, a nucleolus, 
which would invalidate the names used by HenkinG and MONTGOMERY. 
In a recent paper, “A Study of the Germ Cells of Metazoa”, 
MONTGOMERY refers to the question of a name for the unusual 
chromosome and objects to “accessory chromosome” because it is in- 
definite. He prefers to continue the use of “chromatin nucleolus”, 
although he admits that the structure is not a nucleolus but is a 
chromosome, for the very poor reason that it sometimes has the form 
of a nucleolus. The choice between the two terms is merely that 
between inaccuracy and indefiniteness when the latter quality is really 
desirable in the face of the unsettled character of the element. 
Morphologically, the term ‘accessory chromosome” is definite and 
exact, in that it classes the object to which it is applied with the 
formed chromatin elements while, on the other hand, the name 
