106 CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTEKA HETEROPTERA. 



separate in the first maturation monaster. I did not describe the second maturation 

 mitosis. 



9. CcENUs DELius Say. 



Spermatogonic Divisions. — In the equator of the spindle there are 14 chromo- 

 somes (Plate IX, Figs. 53, 54). Ten of these compose 5 pairs of gradated sizes, each pair 

 with components of equal volume {A, a-E, c). Of the remaining 4 I take 2 {F, f) to 

 be another pair of autosomes, though they are not quite equal ; while 2 others still 

 more unequal in size {Di, di) are probably the diplosomes judging from the later 

 history of the chromosomes in the spermatocytes. That all of these elements become 

 halved in the anaphase is shown by the I'ecurrence of the number 14 in a daughter 

 chromosomal plate (Fig. 55). 



Groiuth Period. — The two very unequal diplosomes may be either united during 

 the growth period, which appears more frequent, or they ma}' be separated. 



First Maturation Division. — Eight chromosomes enter into the spindle, and were 

 all shown on lateral view in Fig. Gl of my earlier paper (19015). They are 6 bivalent 

 autosomes that divide reductionally, and 2 separated diplosomes that divide equa- 

 tionally. A pole view of a daughter chromosomal] plate of the early anaphase is shown 

 in Fig. 56 ; the 6 bipartite elements are univalent autosomes with the reopening longi- 

 tudinal split, and the two unipartite bodies in the center are the diplosomes {Di, di). 



Second Maturation Mitosis. — The two diplosomes conjugate in the center of the 

 equatorial plate (Figs. 57, 58), and in the anaphase separate from each other without 

 dividing, while the 6 autosomes divide equationally. 



Literature. — My previous account (1901/>) was incorrect in stating 16 to he the 

 number of spermatogonia! chromosomes, and in considering the diplosomes to divide 

 reductionally in the first maturation mitosis ; then I did not follow the spermatogenesis 

 beyond this point. Wilson has given a full account of the whole process, and my 

 present observations corroborate his in every particular, except that I find the two 

 diplosomes to be by no means always regularly separated from each other in the 

 growth period as Wilson describes. 



10. Trichopepla semivittata Say. 

 Sperraatogonic Divisions. — Fig. 59, Plate IX, is a careful redrawing of the chromo- 

 somal plate illustrated in Fig. 65 of my earlier paper (19016). It shows distinctly 15 

 elements, while the small protuberance Z attached to the chromosome a may be a 

 sixteenth. From the phenomena of the growth period there are to be concluded at 

 least 16 chromosomes for the spermatogonium, in agreement with my former descrip- 

 tion. Twelve, which compose a series of gradated pairs {A, a-F,f), are probably auto- 



