CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA IIETEROPTERA. 105 



Second Maturation Division. — Here there are 6 univalent autosomes that divide, 

 equationally (Figs. 44, 45, A-F). But the diplosomes conjugate in the center of the 

 equator and this bivalent element {Di, di), with components of very unequal vohmie, 

 divides reductionally. Accordingly each spermatid receives 6 autosomes and one of 

 the two diplosomes. 



This is another species where the particular chromosome pairs may be recognized 

 with great precision in each cell generation, as one finds by comparing the correspond- 

 ingly lettered elements in the figures. 



Literature. — I previously (1901?>) concluded there were 16 instead of 14 chromo- 

 somes in the spermatogonia, for I was misled into counting two constricted elements 

 as two each. Further I did not notice that the diplosomes enter separately into 

 the plate of the first maturation mitosis, and did not describe the following mitosis. 

 Wilson (1905a) described and figured this process correctly. 



8. Perillus confluens H.-S. 



Spermatogonic Divii^ion,^. — There are 14 chromosomes (Plate IX, Fig. 46) of which 

 12 form 6 gradated pairs of autosomes {A,a-F,f); while the two smallest elements 

 {Di, di) are not of quite equal volume and are diplosomes as the later history shows. 



Growth Period. — Six bivalent autosomes are formed. The diplosomes also conju- 

 gate but later in the synapsis stage than in the other Pentatomids. Subsequently each 

 becomes constricted, and tliey lie close together and at the same time against the plas- 

 mosome (Fig. 47). 



Fir.it Maturation Division. — In tlie late prophases the diplo.somes separate and lie 

 in the chromosomal plate near each other (Fig. 48, Di, di) ; each divides through the 

 plane of its pi-evious constriction. Fig. 49 shows a daughter chromosomal plate of the 

 early anaphase of this mitosis ; 6 show a line of division and they are univalent auto- 

 somes with the reopening longitudinal split, while the two that show no such constric- 

 tion are the autosomes. 



Second Maturation Division. — On pole view of the spindle (Fig. 50) are seen 7 

 elements of which the central one is really bivalent, formed by the conjugation of 

 the two univalent diplosomes {Di, di). Fig. 51 represents a lateral view of the 

 same stage but showing only 6 of the 7 elements ; the one with the two components 

 of unequal volume is the bivalent diplosome. This diplosome divides reductionally, 

 the autosomes equationally ; consequently each spermatid (Fig. 52) receives 7 elements, 

 namely, 6 autosomes and one of the two diplosomes. 



Literature. — My previous description was erroneous in stating there to be 16 

 chromosomes in the spermatogonia, and in failing to note that the diplosomes lie 



A. p. S.— XXI. K. 21, 7, '06. 



