1901.] NATURAL SCIENCES OF PHILADELPHIA. 261 



FUKTHER STUDIES ON THE CHROMOSOMES OF THE HEMIPTERA 

 HETEROPTERA. 



BY THOMAS II. MONTGOMERY, JR., PH.D. 



The present account deals with the relatioas of the chromosomes 

 in the spermatogenesis of certain Hemiptbva, and is practically a 

 continuation of a previous paper of mine.^ In the present paper 

 will be found a description of the chromosomal relations, as far as 

 they could be determined, in certain species not heretofore ex- 

 amined. 



The material was collected last summer at Woods Holl, Mass. , 

 and was kindly identified for me by Dr. Philip E,, Uhler, of Bal- 

 timore. The testes of some of the species (Tingis clavata, Corixa 

 verticalis, Cyvius luridus, Lygus jnatensis') were fixed simply in 

 Couklin's picro-acetic mixture, and this fixation not allowing suc- 

 cessful staining with Hermann's safiranine-gentian violet method 

 the relations of the nucleoli and of the chromatin nucleoli could 

 not be determined. But in the remaining species {Nabis annulatus, 

 Corizii-s alternatus and Harviostes reflexulus) the testes were fixed 

 in Hermann's platinic chloride-osmic-acetic mixture Avhich allowed 

 the saffraniue-violet stain, so that for these species the distinction 

 of nucleoli and chromatin nucleoli could be made. 



As in my preceding paper (I. c. ) on this subject, the term 

 " chromatin nucleolus " is applied to that peculiar nuclear ele- 

 ment which is a chromosome peculiarly modified in preserving its 

 form and dense structure, which chromosomes as a rule show only 

 in the height of mitosis, throughout every stage of the sperma- 

 togenetic cycle. With the saffranine-violet method, the chromo- 

 somes proper stain red only in mitosis, and violet in other stages, 

 but the chromatin nucleolus maintains the red stain in all stages. 

 1. Tingis clavata Stal. 



Three testes were studied, none of them showing spermatogonic 

 monaster stages. 



' "A Study of the Chromosomes of the Germ Cells of Metazoa," to be 

 published in the Transactions of the American Philosophical Society. 



