No. 4-] MALE REPRODUCTIVE CELLS OF INSECTS. 1 95 



work was carried on in the Hull Zoological Laboratory of the 

 University of Chicago during the summer of 1898. 



The University of Kansas, 



Lawrence, Kan., December i, 1898. 



After the preceding had gone to press, a copy of Montgom- 

 ery's paper 1 upon the spermatogenesis of Pcntatoma was, by 

 the kindness of Dr. Wheeler, placed at the disposal of the 

 writer In it is found a strong support of the views expressed 

 in this paper upon the general character of the accessory chro- 

 mosome -a support which strongly confirms the belief tha 

 this structure will be found very widely distributed, at least 

 among the insects. Without doubt, however, specific varia- 

 tions of some magnitude will be found ; the observations 

 on Pcntatoma and XipJndtum indicates this clearly. Much 

 is therefore to be learned by a comparative study ot different 

 forms, and in this, objects such as XtpJndunn, in which the 

 element occurs with much prominence, will prove most valuable. 

 The results attained by Montgomery, however, are much in 

 advance of any others up to the present time, and agree, m the 

 main, with the appearances noted by the writer in the cells of 

 XipJnduun. These are (i) the resemblance to a nucleolus in 

 the resting stage, and (2) the similarity to a chromosome dur- 

 ing the period of division. Montgomery expresses this briefly 

 in^the following language: "This peculiar structure acted like 

 a nucleolus in the rest stage, but in the monaster is destined 

 to lie in the equator among the chromosomes, where it also 

 becomes divided in metakinesis, and so terminates by acting 

 like a chromosome, as at the commencement it had been 



formed from one." 



There can be no reasonable doubt of the accuracy of these 

 observations when two investigators, working entirely inde- 

 pendently of each other on different objects, reach the same 

 conclusions. 



/.QQ\ Ti,P ';nPrmatoeenesis in Pentatoma up to the Formation 

 1 Montgomery (98), The Spermatogenesis ^^^ ^,^.^^^^ 



of the Spermatid, Zoologische Jahrhucker, Abtheil. t. Anat u s 



Bd. xii. 



