130 CHROMOSOMES IN THE Sl'ERM ATOGENESIS OE THE HEMII'TERA HETEROPTERA. 



the surface of the plasmosome {PI, Fig. 239), and as in the spermatogonium the pairs 

 are of shghtly different sizes. 



First Mahiration Division. — The hivalent diplosonies, 4 in number, are readily 

 distinguished by their small size and lie always upon the periphery of the chromo- 

 somal pUite ; most frequently 3 lie close together, the 4th some distance off from them 

 (Fig. 241) ; or tliey may all be near each other (Fig. '242), or 2 may be situated at one 

 place and 2 at another. These diplosomes with the 12 bivalent autosomes are all illus- 

 trated on lateral aspect in Fig. 240, and all these elements divide, probably reduc- 

 tionally. 



Second Maturation Division — Pole views of the spindle show again 16 elements 

 but in different arrangement in that the 4 diplosomes now lie in the center (Figs. 243, 

 244). Lateral views show that all of these are bipartite, and therefore they all prob- 

 ably divide again though their number could not be counted in the spermatids. There 

 is certainly no conjugation of any of the diplosomes in the second spermatocytes, and 

 no evidence at any stage of the presence of a monosome. 



Literature. — My earlier observations (1901 h) were entirely correct, and I have to 

 add to them simply the account of the second spermatocytes. 



33. SiNEA DiADEMA Fabr. 

 My earlier observations were essentially correct, and the three pairs of diplosomes 

 of the rest stage of the spermatocyte are shown in Plate XIII, Fig. 245, attached to the 

 plasmosome (F/). Another pole view of a first maturation monaster is presented in 

 Fig. 246, the 3 bivalent diplosomes readily distinguishable by their small volumes. 

 Of the 13 autosomes three are always close together and so form a regular complex 

 {A, a, B, h, C, c), just as 1 previously described ; but now I find no reason to consider 

 the central one of this complex quadrivalent, for there is no good evidence that it is 

 anything else than an unusually lai'ge bivalent autosome and it does not behave dif- 

 ferently from the others during the preceding growth period. This central one of 

 the complex is always the largest and a very evident tetrad (/?, h, Figs. 247, 248); 

 close to one end of it is a smaller bivalent autosome (A, o), and close to its other end 

 a still smaller one (C, c) ; these size relations are always the same. All the elements 

 of this mitosis are shown on lateral view in Fig. 247 ; the 3 smallest are the bivalent 

 diplosomes and they are of slightly different volumes. All 16 elements divide reduc- 

 tionally, so that each second spermatocyte receives a univalent component of each- 

 The complex of the 3 autosomes A, a, and B, h, and C, c divides more tardily than the 

 others, as shown by the successive stages of Figs. 248-250, and in these anaphases the 

 lateral autosomes {A, <i and C, c) become separated from the large middle one (B, h). 



