220 KANSAS UNIVERSITY SCIKNCE BULLETIN. 



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 evi- 

 dence is forthcoming the character of the peculiarly modified 

 chromosomes in the spermatocyte of the Hemiptera must re- 

 main in doubt. 



Aside from definite retractions that Montgomery has made re- 

 garding his earlier views on the character of the "chromatin 

 nucleolus," there are noticable different attitudes toward it in 

 his earlier and later works. Thus, in his lecture at Woods 

 Holl (13«) , we find the following : "These remarkable 'nucleo- 

 lar ' 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 in- 

 vestigations it is apparent that he views his "chromatin nu- 

 cleolus" primarily as a nucleolus with chromatic origin and 

 characters, but the fact is equally apparent that he now re- 

 gards it primarily as a "chromosome" with nucleolar attri- 

 butes. This is made evident in his recent definition, which 

 reads: "The chromatin nucleoli are morphologically chromo- 

 somes, undergoing division in mitosis like the other chromo- 

 somes, but differing from them in the rest stage by preserving 

 a definite (usually rounded) form." 



What has here been said regarding the "chromatin nucle- 

 olus" applies to those structures in Eucltistus and other Hem- 

 iptera 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 classifica- 

 tion operative, but by direct statement we learn that Montgom- 

 ery 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 Hemip- 

 tera where one chromosome becomes differentiated into a 



