CHROMOSOMES IN THE SPERMATOGENESIS OF THE IIEMIPTERA HETEROPTERA. 117 



tion to the fact that one of the cliroinosomes of the first maturation mitosis is differ- 

 ent in form from the others, and left the question oj^en whether it might be univalent 

 there (so be a monosome). The subsequent mitosis was not described. 



IS. Protenor belfragei Hagl. 



The previous account given by me (19016) was detailed and entirely correct, and 

 Wilson has recently corroborated it. I have simply to add to it that all the auto- 

 somes of the spermatogonium can be groupedjinto pairs (A, a-E, e, Plate XI, Fig. 

 134), that the diplosomes there are slightly unequal in volume {Di, di), and that the 

 monosome (J/o) is by far the largest element. Another figure (135)iis given of these 

 elements in the growth period. The monosome becomes always longitudinally split 

 in the synapsis period {Mo, Fig. 135), and its division in the first maturation mitosis is. 

 along the plane of this split and not, as I had pi'eviously interpreted it, transverse to its 

 long axis. 



11). Alydus pilosulus H. S. 



Spermatogonic Division. — Four clear pole views showed in each case 13 elements, 

 namely (Plate XI, Fig. 136) : 5 pairs of autosomes A, a-E, e of remarkably different 

 volumes and forms ; 2 unequal diplosomes {Di, di), the smallest of all ; and 1 mono- 

 some {3Io). 



Growth Period. — In the growth period there is a single safraninophilous body of 

 considerable size, that from its singularity and later behavior is undoubtedly the 

 monosome {Mo, Figs. 137, 138), and from the early synapsis on increases to at least 

 twice its original volume, as shown by comparison of the figures. In the postsynapsis 

 it becomes longitudinally split, lies regularly against the nuclear membrane and fre- 

 quently also against a plasmosome. The diplosomes are apparently not distinguishable 

 during the growth period, and therefore it is probable that they undergo much the 

 same changes as the autosomes except for their later conjugation. 



First Maturation Division. — In the prophases the diplosomes {Di, di, Fig. 139) 

 become compact ahead of the autosomes, and reappear as two rounded bodies that do 

 not conjugate until the nuclear membrane disappears. The monosome {Mo) is to be 

 distinguished from them by its larger size. The auto.somes are longitudinally split 

 and bivalent. In the equatoi'ial plate (Fig. 140) there are always 7 elements: 5 

 bivalent autosomes that divide reductionally, and a bivalent diplosome {Di, di) that 

 divides in the same manner as may be readily determined on the basis of its two 

 components being dissimilar in volume. The monosome {Mo) divides lengthwise. 

 The bivalent diplosome is always central, the monosome most excentric. In a number 



