CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA HETEROPTERA. 109 



12. Peribalus limbolaris Stal. 



Spermntogonic Division-':!. —There are 14 chromosomes (Plate X, Fig. 74); 12 of 

 them make up 6 well marked pairs of autosomes {A, a-F, f), and all of these are 

 elongate; the two remaining are very unequal in volume {Di, di), are rounded, are 

 the smallest of all, and are the diplosomes. The gradation in size of the autosome 

 pairs is very marked. 



Growth Period. — During the greater part of the growth period there appears to 

 be only one diplosome in the spermatocytes, and it usually is of rounded form and 

 contains one or several vacuoles ; whether this single one represents both diplosomes 

 of the spermatogonia, or only the larger one of them, I could not positively determine. 

 Towards the close of this period, however, two separated" ones of very dissimilar volume 

 are occasionally found (Fig. 75, Di, di). During the synapsis, unlike the conditions 

 in the other Pentatoraids, these are not safraninophilous but stain violet like the 

 plasmosomes of which there are usually two or three in each nucleus, and for this 

 reason it is then difficult to determine the diplosomes. 



First Maturation Mitosis. — In the equator of the spindle are present always 8 

 chromosomes (Figs. 76, 77) ; the two smallest are the diplosomes which have entered 

 the spindle separately and divide there equationally ; they are dyads. The 6 larger 

 elements are bivalent autosomes, each of which appears as a tetrad with distinct com- 

 ponents when seen from its flattened surface (Fig. 77) ; the longitudinal split of these 

 is parallel to their long axes, the same position as it held in all the earlier stages, and 

 accordingly in this first maturation mitosis the autosomes divide reductionally. A pole 

 view of one of the daughter chromosome plates, from the early anaphase, is illustrated 

 in Fig. 79 ; the diplosomes (Di, di) can be readily distinguished from the autosomes 

 by being unipartite and smaller. 



Second Maturation Division.. — Pole views show api»arently only 7 elements (Fig. 

 78) ; but the central one is seen to be composed of two placed the one immediately 

 above the other {Di, di), which are the now conjugated diplosomes. This bivalent 

 diplosome is more easily recognized upon side view (Fig. 80), and divides reduction- 

 ally, i. e., the larger diplosome {di) passes into one spermatid and the smaller diplosome 

 {Di) into the other, while the 6 autosomes divide through the plane of their longi- 

 tudinal splits. 



Literature. — I had erroneously (19016) stated the number of spermatogonia! 

 chromosomes to be 16, and was consequently led into concluding that there is a 

 bivalent diplosome dividing reductionally in the first spermatocyte division. 



