CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA. HETEROPTERA. 103 



Growth Period. — There are formed in the early growth period 6 bivalent auto- 

 somes, and one bivalent diplosome. In the earlier stages the latter is composed of two 

 of unequal volume placed end to end. Later stages show a nmch larger, ovoid dij^lo- 

 some containing one large or several smaller vacuoles ; I could not decide whether 

 this is the whole bivalent diplosome or only one of its components. 



Fimt Maturation Division. — Pole views^ of the equatorial plate (Fig. 29) show 

 always 8 elements, 6 of which must be bivalent autosomes. Two elements are much 

 smaller, and judging by their size relations in the spermatogonia these must be the 

 diplosomes {Di, di) ; if this conclusion be correct, then the bivalent diplosome must 

 have separated into its two elements in the prophases of this mitosis. The chromosomes 

 are very regularly arranged ; a large autosome forms the center of a circle composed 

 of the five other autosomes and the two dijjlosomes. 



Second Maturation Division. — Pole views show apparently only seven elements in 

 the spindle (Fig. 30) ; but the central one is really bivalent, made up of the two dip- 

 losomes placed end to end ; probabh' this bivalent diplosome undergoes a reduction 

 here, but I cannot say so with certainty because my slides contained only a few of 

 these stages. 



Literature. — Previously (190l?>) I was mistaken in supposing there to be 16 

 chromosomes in the spermatogonia ; I did not describe the second maturation division. 



5. CosMOPEPLA cARNiFEX Fabr. 



Spermatorjonic Divisions. — There are 14 autosomes which compose 7 pairs of gra- 

 dated sizes (.4, a-G, g, Plate IX, Fig. 31) ; and two diplosomes, one of which (Di) is 

 the smallest element of all, while the other is much larger and rod-shaped (di). 



Groivth Period. — The 14 autosomes conjugate to produce 7 bivalent ones. The 

 2 diplosomes also first unite end to end, then more closely side to side ; each of them 

 becomes longitudinall}^ split, and their changes appear to be exactly as described for 

 E%ischistus variolaritis. 



First Maturation Division. — In the late prophases (Fig. 32) the diplosomes sepa- 

 rate, each is bipartite, and they enter into the spindle apart from each other. Both 

 of them divide, therefore equationally, while the 7 bivalent autosomes divide reduc- 

 tionally. On pole views it is difficult to recognize which are the diplosomes (Fig. 33), 

 but on lateral aspects (Fig. 34) they may be recognized as being the two smallest 

 elements and the only ones that are not tetrads. 



Second 3Iaturation Division. — Just before the arrangement of the chromosomes 

 in the plane of the equator the uneqtial diplcsomes conjugate in the middle of the 

 equatorial plate to form a bivalent element, hence one sees either 8 bodies (Fig. 35) 



