If, therefore, Montgomery’s recent observations are correct, it must follow, I think, that his “chromatin nucleolus” and the accessory chromosome are different structures. I am free to admit, however, that his statements are far from convincing. So much dependence is placed upon the numerical relationships of elements that are admittedly very minute, and so little corroborative proof is given, that I entertain serious doubts as to the accuracy of the observations. In this connection I would suggest a comparison between the figures of the “chromatin nucleolus” in the first paper upon _Euchistus_ (figs. 55–68) (=12=) and those in the last one (figs. 1–17) (=15=). The showing here made would alone be sufficient to raise a question as to the nature of the “chromatin nucleolus,” and until further evidence is forthcoming the character of the peculiarly modified chromosomes in the spermatocyte of the Hemiptera must remain in doubt. Aside from definite retractions that Montgomery has made regarding his earlier views on the character of the “chromatin nucleolus,” there are noticeable different attitudes toward it in his earlier and later works. Thus, in his lecture at Woods Holl (=13=_a_), we find the following: “These remarkable ‘nucleolar’ structures which stain like chromatin have been observed by numerous writers, but as yet no satisfactory description has been given of their mode of origin. They have been observed by me in spermatocytes of various insects, in hypodermal and other cells of _Carpocopsa_, and in follicle cells of the testicles of _Plethodon_ and _Mus_.” At this early stage of Montgomery’s investigations it is apparent that he views his “chromatin nucleolus” primarily as a nucleolus with chromatic origin and characters, but the fact is equally apparent that he now regards it primarily as a “chromosome” with nucleolar attributes. This is made evident in his recent definition, which reads: “The chromatin nucleoli are morphologically chromosomes, undergoing division in mitosis like the other chromosomes, but differing from them in the rest stage by preserving a definite (usually rounded) form.” What has here been said regarding the “chromatin nucleolus” applies to those structures in _Euchistus_ and other Hemiptera to which Montgomery has given the name without qualification. According to his definition, however, there is present in the cells of _Protenor_ and other species another form, the “chromosome x.” Not only by inference is this classification operative, but by direct statement we learn that Montgomery regards this element as a member of the class of bodies which he calls “chromatin nucleoli.” In speaking of _Protenor_ chromosomes, he says: “This is the only case in the Hemiptera where one chromosome becomes differentiated into a ‘chromatin nucleolus’ for the first time in the spermatocyte generation.”