102 CHROMOSOMES IN THE SPERMATOGENESIS OP THE HEMIPTERA HETEROPTERA. 



3. PoDisus si'iNosus Dall. 



SperriitiUujonk- Divisions. — There are 16 chromusomes in the equator of the si)in(lle 

 (Plate IX, Fig. 23). Fourteen of them make up 7 pairs {A, a-G, g), and the pairs form a 

 gradated series. The 2 others are the diijlosomes which ai-e of unequal volumes, one 

 of them {Di) being the smallest of all the chromosomes while the other (di) is as large 

 as the components of the smallest autosome pair. 



Growth Period. — The 14 autosomes conjugate to form 7 bivalent ones. The 

 diplosomes likewise become apposed and during the synapsis stage and a part of the 

 later portion of the growth period this bivalent diplosome is placed against the nuclear 

 membrane and is composed of a larger and a smaller element in close contact (Fig. 

 24, Di, di), but usually, as in the figure, a narrow line of separation is to be seen 

 between the two. 



First Maturation Division. — In the late prophases the diplosomes separate, and 

 are apart from each other in the equatorial plate (Fig. 25) ; the smallest element there 

 is the smaller diplosome {Di), but which element represents the larger it would be 

 difficult to determine from the size relations. Each diplosome divides in the plane 

 of its transverse constriction, which can represent nothing else than a longitudinal 

 split. Each of the 7 bivalent autosomes divides reductionally. 



Second Maturation Division. — In the center of the spindle the diplosomes conju- 

 gate end to end ; Fig. 26 shows a pole view of all the chromosomes, and in the center 

 can be seen a smaller diplosome placed at the end of a lai-ger {Di, di) ; lateral views 

 (Fig. 27) show clearly this bivalent diplosome with its unequal components. This 

 bivalent element divides reductionally, while all the 7 autosomes divide equationally. 



Literatare. — My preceding account (19016) was entirely correct excej^t that I 

 failed to note the unequal volumes of the diplosomes and the phenomenon of their 

 being separate in the first maturation monaster ; I had figured and described the 

 second maturation monaster in mistake for the first. Wilson (1905o) was the first to 

 show the conjugation of the diplosomes in the second spermatocyte, and their reduc- 

 tional division there. 



4. MoRMiDEA LtiGENs Fabr. 



Spermatogonic Division. — There are apparently 14 chromosomes in the spindle 

 (Plate IX, Fig. 28); this is a redrawing of Fig. 31 of my precedijig paper (19016) in 

 which I had erroneously represented each of the two largest elements A, a as two. 

 There are 6 autosome pairs, A, a-F, f, which show gradations in volumes ; only in 

 regard to the supposed pair E, e am 1 undecided whether it is a single or two chro- 

 mosomes. The two smallest bodies are the diplosomes {Di, di) and are unequal in size. 



