CHROMOSOMES IN COREID HEMIPTERA. 9! 



double, arranged in an irregular ring with one in the centre and 

 one or two outside. Unlike the first spermatocytes, the central 

 chromosome i- not the w-chromosome bivalent but one of the 

 larger ones, while the w-chromosome itself lies just within the 

 riii'.. I ig. 3, -, /and h) or somewhat outside (Fig. 3, g). In these 

 lour meiapha-e-., the axis of the spindle is somewhat oblique to 

 tin- plane of section and the structure of the chromosomes can 

 thus bt- readily obsemxl. As might be expected many have the 

 -hape o| t \pic.il tetrads foreshadowing the two oocyte divisions. 

 Thi- i- r-prrially well seen in Fig. 3, e, where even the w;.-chromo- 

 some has the quadripartite form. Whether distinctly quadri- 

 partite, or -imply dumb-bell shaped, the plane of the first division 

 le.irly indicated in every chromosome. In Fig. 3, e and //, 

 tin-re are t\\o bivalents (M and A T ) perceptibly larger than any 

 ot the- other-. In all probability these arise from a pairing of 

 i he | < ii ic 1 chromosomes of the oogonia. Accordingly one 



o| i In in m.i\ lie- considered to be the idiochromosome bivalent. 



The anapha-e of the first polar spindle was found in < 

 diceiiK .liter laving. y The- chromosomes divide in the plane 

 ahradv indie ated at metaphase. Fig. 4, a, shows a side view of 

 louc i hioiiio-tniie- in initial anaphase; the tetrad character of 

 e.u h i- ( le.uK indicated. Fig. 3, i and j, shows polar views of 

 i he outer and inner groups respectively from the same spindle; 

 ea ( h ha- i i chromosomes. All, with the exception of the ni- 

 ( hromosome in j, are obviously dyads showing all degrees of con- 

 striction, as in the first polar ana phase of Archimerus. The outer 

 group \\hirh passes into the first polar body shows two dyads 

 completely di\ided though the polar body itself neither divides 

 nor form- a -pirn lie. lu both groups two largest dyads (M and 

 N) can be distinguished. Fig. 4, c and <7, are outer and inner 

 group- iv-pert i\ely from another spindle, in slightly oblique pol.ir 

 \ ie\\ in ( - the large chromosome, A T , was found in the same section 

 as tin inner group, d). Both groups contain II dyads of which 

 t\\o i M and .Y> are larger than any of the others. Fig. 4, e and 

 Me outer and inner groups respectively of a third anaphase in 



A Millie i-Mi-1'ti..n to this was found. One egg taken from the lowest part of 



tin- .'Yicliut >li(\scil tin- first polar spindle in initial anaphase It is possible that 

 n.uuli liaiKllinv; -tan.',! the maturation process, as has been found in other groups 

 of aniin 



